Justin Bieber Wears a Disguise in Amsterdam

Justin Bieber is a man of many looks ... but his latest might be his most epic.

The Biebs was out in Amsterdam Friday sporting a wig, glasses and a classic porn 'stache with matching goatee. The only problem -- JB did a poor job covering up his signature tats -- but to be honest, they're a perfect fit with the look.

Further proof ... things get weird in Amsterdam.