What is crab fuck?

when you put your legs through the sleeves of an oversized sweater(upside down), then put your arms inside of the sweater, pull the sweater over your head and crouch down

"dude did you see drake he was totally fucking crabbing yesterday"

crab fuck - video

Crab fuck - what is it?

A sexual position in which the woman is in a crab-walking position with the man lying under her.

I really enjoyed crab fucking my girlfriend last night.