sit in with
Advanced (C1) neutral
to join another group for a short time
"A jazz pianist sat in with the band for the final set."
Hear it in context
Every Steve Harvey Appearance on ‘Ellen’
TheEllenShow · 175:58
I'll just sit in with some cocoa or something like that.
What does Chelsea need to do to get back on track? | Premier League | NBC Sports
NBC Sports · 3:34
are on such long-term contracts that they can't just sit in with