Better idea: Everyone with a big white truck should put the letters in bold: ICE on their doors.
Some years back, an ER nurse in a big Texas city wrote that one Saturday evening there was hardly any foot traffic, when usually the Mexicans would be pouring in with anything from various wounds from bar fights to a child's runny nose.
No one could figure out the drastic drop. On her break, the nurse went outside for some fresh air and noticed that someone had illegally parked their van right near the door. It was the same color as the La Migra vehicles.
She said it became the standing joke that when the ER felt overwhelmed, they would park a green van outside.