Antman

Inserting the flaccid penis into the anus of another person then proceed by getting erect.

You: Babe I wanna try anal
Girl: No I'm scared it's gonna hurt.
You: can we try the AntMan
Girlfriend: Is it gonna hurt ?
You: I'll be flaccid
Girlfriend: Okay !
seconds later
Girlfriend: OW BABE I THOUGHT YOU WERE FLACCID !
You: Doesn't AntMan get bigger though ??