John Travolta and Robin Williams once crashed a wedding together
The American actors decided after a night of drinking together in Santa Barbara, California, they would join in with the celebrations next door to the bar they were at.
John said: "We were having fun, starting to relax, when we saw there was a wedding next door. We figured we`d crash it."
At first, guests didn`t realise the actors - who were both TV stars in the late 70s, when the nuptials took place - were the real stars of shows `Welcome Back, Kotter` and -Mork and Mindy`.
John, 55, added: "They figured out who we were. Some guy yelled out, `Hey, they really are Mork and Vinnie Barbarino!` "
The pair were reunited on the set of their latest film, comedy `Old Dogs`, but their off-the-wall antics and on-set jokes proved too much for some of their co-stars to cope with.
John`s wife Kelly Preston, who plays Robin-s love interest in the movie, said: "The hardest part of being in a scene with any of these guys was not laughing and ruining every single take.
"And if you did laugh, the director just let us go with it, because they`re going to be goofy and try to make you laugh."
`Old Dogs` - which is released next March - follows a pair of ageing sports stars played by John and Robin who are charged with looking after a pair of seven-year-old twins Robin-s character never realised he fathered.