to get something to eat quickly, usually a small or casual meal
Shall we grab a bite before the film?
I didn't have lunch, let me just grab a bite quickly.
We grabbed a bite at the airport. (a quick, casual meal) We sat down to a big dinner. (a full, leisurely meal)
Common mistake
✗Let's grab a bit to eat.
✓Let's grab a bite to eat.
It's 'a bite' (a small amount of food), not 'a bit'.
Tell it apart
We grabbed a bite at the airport.
a quick, casual meal
We sat down to a big dinner.
a full, leisurely meal
Often extended to 'grab a bite to eat'. Sounds natural and relaxed.Not for a proper sit-down meal — for that use 'have dinner/lunch', not 'grab a bite'.