Although the world is certainly often unfriendly, the car seat business seems to be an urban legend:
http://www.snopes.com/crime/gangs/carseat.asp
as does the bit about the eggs:
http://www.snopes.com/crime/warnings/eggthrow.asp
Always nice to have a few less things to worry about!
—tkoed
Yep! The police are often the first ones fooled by these rumors.