Your clit belongs to your girlfriend.
Put in a buttplug of your choice to begin stretching your hole. Use a timer to see how long it takes you to make your girlfriend cum using only your tongue.
Spoiler:
Then, here’s the fun part, bend over and use your hands to hold your cheeks open. You girlfriend now gets to fuck your ass with the vibrating strap on for the amount of time it took you to make her cum.
She can go as hard as she likes to make it more painful than pleasurable for you
.
You are not allowed to touch yourself during this dare.