旅の恥はかき捨て
Meanings
1
once over the borders one may do anything; what happens in Vegas, stays in Vegas; shame on a journey can be scratched away
Proverb meaning that when traveling, one can act without worrying about reputation or shame, because strangers won't know you and any embarrassment can be left behind. The literal image is of scratching away shame like dirt.
They say 'once over the borders one may do anything,' so it's okay to let loose a little in a place where nobody knows you.
Wearing flashy clothes while traveling is also in the spirit of 'what happens in Vegas, stays in Vegas.'