travel truncheon

Unwanted erection caused by vehicle vibrations during a road journey.

I can’t get up out of my seat; I’ve got travel truncheon!

fanny grabbers

Your hands.

Get your fanny grabbers out of my popcorn!

nip yer bobie

(Pinch your penis (The end of it))

Husband: I’m bursting fur a pish! (Eng: I’m in desperate need of a wee).
Wife: Nip yer bobie, I’ll stop the car when a find a toilet (Eng: pinch the end of your penis (to hold it in), I’ll stop the car when I find a toilet).