Because you're a rolling advertisement!

[Mikkel]

Next time will whoever it was know to wear gloves , and perhaps use a few more stickers.

[wolfie]

Don't know if this would work for bumper stickers, but I've had good results taking off old IFTA stickers (trucker thing) using a plastic putty knife/scraper, didn't scratch the paint.

[MoonCat]

Rub it on with a cotton swab, let it sit for fifteen minutes, then gently rub with a warm, wet cloth.

Hmmmm....nope, not gonna go there.

Seriously, I can't believe she didn't know those stickers were there. But then, some people can be totally oblivious to anything farther away than their own nose.