I don't know if this has been posted in the past, but it was new to me. About a tenth of the way down this page you can find clear evidence of Julia's ticklishness. Enjoy....
http://www.ninjajournalist.com/entertainment/pretty-woman-fb/
Hey DDD! Always good to see you on the Forum!
This is actually one of the oldest hoaxes on the TMF, sorry to burst anyone's bubble.
The origin of this story comes from.......here! Someone from here went into IMDB (or another similar page) and added "Trivia" to the page, as well as posting here, that on the DVD Garry Marshall tells this story.That's how this info was originally presented, including in it's original wording on IMDB.
Well, you can guess what happened next. Everyone (including me) checked out the DVD and there was no such story. If you search the Forum I'm sure you can find it.
The "Ninja Journalist" (which obviously means just surfing the web) obviously found this "trivia" on whatever page it was housed on and took it at face value.
If you go look at the scene - the scene that was supposedly done in one take - it sounds so obviously nothing like a ticklish laugh, and you can clearly see that no one is near her.
This was hashed out on the Forum years and years ago. I can't find the original thread - most definitely lost in the first year or two of threads and posts that Psycho deleted when he became a religious fanatic - but the "hoax" is alluded to in these threads. This same bit of info re-surfaces every couple of years because of that one IMBD "trivia" page, and if you seach Julia Roberts, you'll see tons of threads just like the one we're on now.
http://www.ticklingforum.com/showthread.php?264854-julia-roberts-tickled&highlight=Julia+Roberts (here Milagros and others watch the scene and determine no tickle laugh)
http://www.ticklingforum.com/showthread.php?104017-Julia-Roberts&highlight=Julia+Roberts (a mention of the DVD commentary which was supposed to be the source of this info....nontkl was my old account, full disclosure)
*****
HOWEVER......during the filming of "The Mexican", it
was reported in the National Enquirer (again, not the most reliable of sources) that the word from the shoot was that Julia Roberts got ticklish every time she had to a love scene with Brad Pitt. (see below) There's also a pic with Mel Gibson (see below) that seems real to me. There
is a pic with Garry Marshall (see below) that comes close...but I think no cigar (I don't think that's a tickle laugh but debateable)
The early TMF was filled with "hoaxes" like this, people posting they tickled celebs and that there was hidden stuff on commentary tracks where you go and check and nothing's there...and you've just wasted two hours listening to a commentary track! lol
With the caveat that unless they had to restrain her somehow, she is probably not ticklish on her feet. 
