You shouldn't do it publicly and with your name and face with it. You aren't legally allowed to. But that is far away from "can't". Hardly anyone is going to s

You shouldn't do it publicly and with your name and face with it. You aren't legally allowed to. But that is far away from "can't". Hardly anyone is going to stop you from drawing a moustache on a poster or from stickering a snarky remark over an ad or from spray painting your opinion about some advertised product on said ad.