Colored tint or even worse mirror tint.

And on the subject of stickers, my brother has some awesome ones on his lifted Jeep Cherokee.

They range from the usual "LIFT IT FAT CHICKS CAN'T JUMP", to an awesome "IF I WANTED A HUMMER I'D HAVE ASKED YOUR MOM" to the all time great "WORK HARDER. MILLIONS ON WELFARE DEPEND ON YOU."

The reactions are priceless. Especially considering the area we live in, which has a high percentage of welfare bums.