My current favorite "jumping out to get a tip" sort of thing that really bugs me is a practice of Washington D.C. cabbies. They're allowed to charge you extra for helping you to load your bags into the trunk. Okay, you're arriving at the airport, carrying your bags yourself, and the cabbie offers to grab your bag and move it the last meter into the trunk, which you could well have done yourself. Extra charge on the meter.

Now I feel like I should brush off their offer to be helpful, and that's seemingly not right.