Mark Ballas

It's not safe to be a 150 lb. reality star these days. During last night's pre-tape of "Dancing With the Stars" -- yes, folks, none of yesterday's performances were live! -- Julianne Hough smacked Mark Ballas in the head during their routine, catching him right on the nose with the top of her…

Mark Ballas has no idea what the heck is going on at his own set -- looking genuinely surprised and mortified when a photog told him about her botched motor lube injections. Kristi Yamaguchi's partner also verified TMZ's story that the pros sometimes get outside help, but said the "stars" can't be…