Hmmm. I'm thinking you need to earn it your erection.
I think you need to earn the right to have an erection tonight.
Would you like to rub my legs?
You would?
Ahhhh, but your hands ....they're still cuffed behind you.
How about you lick my legs instead.
Go ahead. Use your tongue.
Start licking my legs. Lick every inch of them.
You better do a good job.
If you do a good job, maybe I'll let you have an erection.