To make dull explosive sounds.
To move or travel whilst making such sounds.
We were chugging along a back road when the engine cut out.
To drink a large amount (especially of beer) in a single action/without breathing; to chugalug. People usually chant this at the person who is drinking.
Chug! Chug! Chug!
To solicit charitable donations on the street, particularly in a persistent manner.
I got chugged in the town centre today.
The sound of something that chugs.