Degrading Tattoo Challenge

Cassie arrives home from work and wiggles out of her jeans. Pulling down her panties, her spreads her cheeks and exposes herself to you, revealing a glittery heart where her butthole should be. You **** yourself to smile and nod. She smiles back, then goes upstairs to remove the plug and get changed.

When Cassie returns downstairs to the living room, she finds you waiting for her with three objects - the larger 'punishment' dildo, a bottle of lube and a piece of paper. She frowns.

"I... Haven't broken any rules! I'm sure! I've followed them all to the letter."

"This is... Another request." You say delicately. "I've been looking online, and lots of anal only women get tattoos to confirm their long term commitment to the lifestyle. I was hoping you might be ready to make such a commitment."

Cassie hates tattoos. There's no way she'll say yes.

"You know I hate tattoos, right?" Cassie looks unimpressed.

That leads perfectly into the rest of your recital. "Yes, which is why I thought it could be even more interesting to make it into a little game that you and the Butt Buster here can play. The longer you can keep him inside, the less outrageous a tattoo you get."

You gesture to the piece of paper. Cassie picks it up and reads it out loud.

"Over 2 hours: Crosshair surrounding my butthole. Oh I see, that would be easy to hide, if somewhat painful to have done, I imagine.
Over 90 minutes: The words 'Anal Only' surrounding my butthole.
Over 60 minutes: 'I prefer it in the ass' above my pussy. Very embarrassing, but again, nobody should see it unless they see me naked.
Over 45 minutes: 'Put it in my ass' on one butt cheek. I'd need to be careful what underwear I chose.
Over 30 minutes: 'Butt slut' in giant writing over both butt cheeks. No thank you.
Over 20 minutes: 'Anal slut' on my lower back. Very difficult to hide at all times. There's no way I'd get away with this never being spotted. Unthinkable.
Over 10 minutes: 'I <3 anal' on my inner wrist. Can you imagine! Does anyone even really have something like that?
Under 10 minutes: All of the above. Haha, good joke."

Cassie discards the list back on the table.

"Is that a no, then?" You say happily.

"I haven't decided." Cassie looks unamused but for whatever reason isn't saying no.

"I'll do the challenge first, then see what I get, and then decide. You know I love a challenge." She gives you a dry smile.

Cassie! You don't have to do this!

But Cassie is already lubing up the big dildo in preparation, and you're not allowed to discourage her from proceeding. You watch her slowly begin to insert it, wincing as she does. You wince too. That thing looks tough to handle.

But handle it she does. A few moments later, she is forcing the last of it inside her, and replacing her panties to help keep it inside.

She turns to you with a pained expression on her face.

"Start the timer."