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Happy National
Underwear Day!:
Rihanna Steps Out in
Underwear -- 8 Other
Celebrity Offenders

To celebrate National Underwear Day (yes, this is a real thing), we've rounded up nine pics of celebs showing off their undergarments in public.

From Lady Gaga to Selena Gomez, is seems everyone in Hollywood is trying out this strange trend! And we're really not sure why...

Anyway, click through the gallery above to see the pics!