I dont think this should be a power, if it was made it should be a FREE feature, plus users could edit the text after and make it be a inapp word! (guessing it be a different packet sent if edited message, bots might not pick this up)
Powers like this are most likely pre planned, its near Halloween so boo was most likely a planed power for Halloween at some point. It was obvious that this power would be made at some point!
So no this wasn't based off Zukes suggestion