From D.L McCulloch & L.E McCulloch:
Tip 'n' Fart is a tip calculator and a fart machine in one. Now you can tip and fart your way through any bill or restaurant.
The tip calculator will calculate your part of a shared bill even if you're paying for more than one person, and will calculate your tip accordingly.
The fart machine makes for a great gag with girlfriends, at your local gym or anywhere where there are unsuspecting victims. You'll get numerous different fart sounds from bottom out to wet and messy, and I'll add more as time goes on.