I've found two meanings.
1.
hamming it up
A classified word for flatulence, or fart.
The type of fart that smells like bologna. Quite awful.
Hamming it up is an awful smell, consisting of a bologna-like smell coming from the arse.
2.exaggerate one's acting, to show expressions or emotions more obviously than is realistic Here's a picture of Philip hamming it up for grandma when he was only three.
Usage notes: usually said about expressions made to amuse others

Думаю, речь идет о втором значении. Возможно "Переигрывать"?