Mother Monster had a little incident on stage. Lady Gaga put Justin Bieber to shame this weekend ... barfing MULTIPLE TIMES on stage during a concert in Spain .... WITHOUT MISSING A STEP!!!!

Gaga was in the middle of her hit "Edge of Glory," when she bends over with her back to the stage and starts blowin' chunks ... and then immediately pulls herself together and starts dancing again! Gaga was suffering from the Flu but didn't want to cancel the show. Lady Gaga took it like a champ.

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