glonging
To collapse into your seat at the theater thereby hitting the knees of the unfortunate person behind you.

A dangerous practice that might cause you to be sued for personal injury.

Pronounced with a soft "g" in the middle, as in "plunging", "lounging", "fringed" and "margin".
"Hey, lady! Will you puh-leese stop glonging back into your seat? You're hurting my knees."