Thinking that you should be able to walk around with a big dick outline in your pants without repercussions is such a pooner way of thinking. The only men comfortable with showing that off in public would be complete perverts, and even those would understand that they're risking getting beat up or having the cops called on them.
So what if those eight your olds go around telling that you showed them your penis and you were clearly having an erection? When the police ask, you just tell them you carry a big dildo in your pants you call Mr. Limpy which goes everywhere you go, like past children's playgrounds, and they'll understand.
It's not like they'll tread you like a man or anything.