And then there's a guy I used to work with who goes to the baseball games when he can. When he does a beer run he rounds up to the nearest $5 and then adds a $20. On his next run when he gets to the back of the beer buying mob he shouts and waves, then by the time he squeezes through the crowd the tapster has dropped everything and is waiting for him with his beers all set to go.
Tipping well opens all sorts of doors and makes things run smoothly: