There are some things you just don’t do. It doesn’t matter how unconventional you may think you are or how desperate you are to get a message out there. Some lines are simply not meant to be crossed. Last week, a group of pro-Palestinian Israeli activists chose to demonstrate against Israeli policy in Gaza by spraying graffiti on one of the last remaining walls of Poland’s Warsaw Ghetto. The group, without a doubt, crossed that line. The left-leaning protestors held a rally near the wall and then sprayed graffiti in Hebrew and English calling for all ghettos — including Gaza...