Not quite fisting someone, where you have all 4 fingers and thumb inserted, but are only able to achieve penetration up to the base of the fingers.
Etymology: Put your fingers and thumb together so they all meet at the tips. Include a back-and-forth motion from the wrist, and your hand looks like a bird eating.
"Brah, I took that chick home last night."
"Oh yeah, did you get laid?"
"Nah. I did feed the bird, though."