Put it in her ass.

You place your cockhead against her asshole and she shivers. "You know what I like, Tiger." She says breathlessly, and pushes back as you push yourself in.

Her tight asshole surrounds your cock, and she grips at the wall. "Oh yesss...." she moans. "Put it all the way in. Fuck that tight little ass." Of course you oblige, sliding out slowly and then back in--and she slams back into you, taking you to the hilt.

"Nice and hard, Tiger. Fuck that tight little ass nice and...oh...and hhhaaarrrddd..." She shivers, her muscles clenching and spasming around you, and closes her eyes. As you start pushing into her more swiftly, she matches your pace, and soon you are fucking that rounded, perfect ass in earnetst. The blonde nurse braces herself against the wall with one hand, clawing at the door, and using the other hand to grope her huge, rocking tits through her white uniform and and alternately rub her clit and finger your plunging shaft and your balls.

In no time at all you and the nurse are wildly fucking right in the hallway, you plunging your cock into her asshole again and again, harder and harder as she groans and squeezes on you and tosses her head. "Oh God, oh fuck, oh fuck yes, fuck yes, fuck, fuck fuck fuck fuck fuck FUCK FUCK OHHHH!" She arches, tensing, her ass clenching down on you as she cums.

The situation, her tightness, and the sight of the big-titted, blonde nurse cumming around your cock just outside the room where you were going to donate is too much for you to take. You feel yourself about to explode, and you know it's going to be one of your most powerful ever.