verb
kibitz
KIB-its/ˈkɪbɪts/
To make casual comments or offer unsolicited advice during an activity.
The spectator kibitzes by pointing out a move in someone else's chess game.

Etymology
The lapwing had a folk reputation as a meddler. Its name underlies the expression for watching a card game and offering unwelcome advice, later extended to unsolicited comments more generally.
More examples
- Please stop kibitzing while I decide my move.
- The spectators kibitzed throughout the card game.
- She enjoys kibitzing even when nobody asks for advice.
Forms
kibitz · kibitzes · kibitzed · kibitzing
kibitzer noun — a person offering casual unsolicited comments