to push the side of someone's body quickly with your elbow (= the middle part of the arm where it bends) often as a way of sharing a private joke with that person or to get their attention

He was sitting next to me so I dug him in the ribs, hoping he'd shut up.

Melissa could see what was happening and dug me in the ribs as she walked past.

She sidled over and dug me in the ribs.

She laughed and dug him playfully in the ribs.

I wasn't near him when he said such a rude thing or I'd have dug him in the ribs.

See also: dig verb (PRESS)