Julia Roberts

I'm not sure of the original source for this, but it's on IMDB, Wikipedia, and multiple listicle-type sites. Here's the quote from IMDB:

"While shooting the scene where Vivian (Julia Roberts) is laying down on the floor of Edward's penthouse, watching old I Love Lucy (1951) re-runs, in order to achieve a genuine laughter, Director Garry Marshall had to tickle Roberts's feet (out of camera range) to get her to laugh so hysterically."

Do with it what you will.

Very interesting that the director did it himself.

I've always likes this shot of what I think is Julia being tickled. I guess it could be debated, but I think it is.