The word 'Yid Army' is used by the Tottenham Hotspur soccer team, and it is pissing people off. Jewish fans don't like it and feel they are being degraded by the racial slur.
They have been asked to stop, but they aren't quite happy about stopping. People are comparing it to the N word or the F word. Jewish fans, it seems, are split down the middle.
So, if you care about London or anything across the pond, here ya go.