An excuse to push her further.

"Hey Mrs O'Brien, you can swallow that now if you want."

Kelly gulps slowly, then wipes her lips before looking at you. "Thank you. I don't know how much longer I could have held it."

"Yeah, it looks like you were drooling quite a bit there. Got it all over my arm too. Think I'd better take it to the bathroom to clean up."

"I'm right there with you," she chuckles and starts walking up the stairs.

The first thing she does in the bathroom is grab her mouthwash to gargle. After spitting the mouthwash into the sink she gargles a second time, and reaches for a washcloth to wipe your cum off her skin. "Didn't you say you wanted a shower earlier? It's kind of all over you, I think you definitely need one now. Let's hop in and clean up."

"Let's?" she asks. "You want to come in with me?"

"I'm still a bit dirty from that blowjob. And you know how I feel about being separated from my arm."

"I know that, but it's inappropriate. You're not supposed to shower with your friends' moms."

That she's worried about that after what she did to you in the kitchen makes you chuckle. "I'm not supposed to get my cum on them either. Or do this," you say as you press your lips on hers. Kelly opens her mouth to reciprocate, and you enjoy the feel of her lips and tongue for a minute.

"Well, maybe not to your other friends' moms," she says when you break the kiss. "Unless you own their mouths too. You know what, just make it quick and keep your hands to yourself, alright?"

"Yes ma'am," you say and turn away to undress. It feels like a pointless gesture since the next thing you do is face her as you get into the shower together, but you don't want to be too brazen at this point . The way you're staring at her now probably makes her uneasy enough, if you treated this like a strip-show she might have backed out and told you to take turns in the shower.

But once you're crammed into the shower together and she's turned on the water, you can't help asking, "How'd it taste, by the way?"

Kelly thinks about her answer. "It's cum. It's fine if you only have to taste it for a couple seconds, but you made me hold it for half an hour. It felt gross, and not just because of the mess it made."

Interesting. So she accepts that her mouth is yours to do with as you please, and doesn't try to talk you out of using it, but she can object to how you use it? "Tell you what, I'll let you swallow it right away next time. Now I'd love it if you could tightly wrap my arm around me and kiss me again."

Not wanting to appear ungrateful, Kelly nods and pulls your wet body against hers. You feel her flinch when your dick makes contact with her thigh, but she can't bring herself to loosen her grip. Nor can she protest since her tongue is busy wrestling with yours. But when the blood flowing into it makes it begin to point up between her legs, she knows she has to do something. Reaching down with her other (or only, now that you own one of them) arm, she wraps her hand around your growing erection, catching it just as the tip touches her pussy.

You gasp at the contact, but it only lasts a second as Kelly adjusts her grip. Then she pushes down gently, aiming your erection into the gap between her slightly spread legs so it touches nothing but her hand. You're a bit disappointed, but her soapy skin still feels good enough that your hips automatically start moving. Slowly, you thrust against her. When she doesn't react, you pull back and do it again. Seeing that she isn't going to stop you, you let yourself fall into a rythm of moving your hips back and forth.

After several minutes of this, you can tell Kelly is getting impatient. You'd promised to make the shower quick, she's not happy that it's turned into a makeout session and she's even less enthused about letting you masturbate with her hand. But since there's no use complaining about it, she decides her best bet is to speed things along. Gathering her resolve, she adjusts her grip again and begins moving her arm. You can hardly believe it, Mrs O'Brien is stroking your cock just an inch away from her pussy. The movement of her arm transfers to her breasts, making them rub against you.

Since there's so little room to maneuver between your bodies, she inadvertently presses your glans up occasionally, rubbing it between her folds before quickly pushing it down again. You can't take this stimulation for long. You erupt shooting cum against the wall behind her. Kelly breaks the kiss and pants wordlessly, still holding your dick to make sure none of your sperm smears into her. Only when you step back, dislodging her other arm from around your back, does she let go.

It looks like Kelly wants to say something, but then she steps out of the shower, wraps a towel around herself, and hurries out of the bathroom, leaving you to clean yourself up.

While you're drying yourself off with another towel, you think about what just happened. Your best friend's mom gave you a handjob, and not even with the arm you'd written on. You wonder what else you can get her to do. You know you could make her yours whenever you want, but it might be more fun to see if you can manipulate her without claiming any more body parts.

You just have to refresh the words you already wrote on her before you leave. She definitely regained control of her mouth again when you finished, hopefully the same isn't true for her arm.