always have at least 2 bags
Used bag 1 on prev flight. (volunteer work for Air Force Cadets)
Pale face, sweating. "You are not going to hurl all over my dash. Take your shoe off."
It worked.
Headset bag (THEIRS, NOT YOURS) is another good alternative.
Heard of a no warning chunder where all the instructor saw was bloggs open his window and let fly. Instructor's window was open at the time and he only got it half shut before portions from the student's side whipped around in the slipstream. (Good reason to fly in balance!)
Saw cadet bragging about being the next Maverick. Big talk. Watched aircraft rotate (1st lesson), 50ft power off, land, inbound call including request for clean up due power chuck all over the dash.