What it means
Tells someone to do their fair share instead of letting everyone else do the heavy lifting. You’ll hear it at work, in group projects, in house shares, anywhere people are meant to muck in. Pulling your weight means you’re reliable and getting stuck in. Not pulling it means you’re dead weight and everyone notices fast. It’s a polite warning shot.
Usage examples
"If Dan doesn’t start pulling his weight on this job, I’m telling the gaffer. Bloke’s done one email and three tea runs, and he’s still knackered."
"If everyone pulls their weight we'll have the place tidy by noon, so no hiding in the kitchen, Gary."
"She never pulls her weight on group projects, then acts surprised when nobody wants her in their team."
"Oi, if you're living here too, pull your weight and wash your own dishes. The sink's not your personal museum."
"We all stayed late to finish the pitch and Kev vanished at four. Next time he can pull his weight or jog on."
Where it comes from
It comes from rowing. In a boat, every rower has to put in enough force on the oar or the whole crew loses pace. That literal idea of carrying your share of the load drifted into everyday English, where it means doing your part instead of letting everyone else slog for you.