Ellen DeGeneres gets a kick out of scaring the living daylights out of her guests -- but superstar Julia Roberts got the V.I.P. treatment ... by getting spooked twice!
The 44-year-old "Mirror Mirror" star was a guest on today's episode of "The Ellen DeGeneres" show, where Ellen not only surprised her by hiding in her bathroom ... but also had a male employee dressed as "Snow White" creep out on set for a second scare.
"I changed because I peed in my pants," Julia said after Ellen freaked her out. "You cannot tell…. I screamed like I was being mugged on a subway."