Crystal donned a white sweater, jeans and sneakers, and took a photo of himself in a low squat, putting it side by side with a near identical looking moment in the movie.
He simply captioned the images "Thank you all…" on Twitter.
‘WHEN HARRY MET SALLY...’ DIRECTOR ROB REINER REVEALS WHY THE ROM-COM STILL RESONATES WITH FANS
Crystal has had his share of memorable roles, from "The Princess Bride" to his work on "Saturday Night Live" and hosting the Oscars, but "When Harry Met Sally" is perhaps his most iconic work.
"When Harry Met Sally" celebrates its 34th anniversary this July. Last December, the film was selected by the Library of Congress for entry in the National Film Registry.
In speaking with the Library of Congress about making the movie, Crystal said, "I just felt so plugged into the process of making the movie… Not that anything is ever easy, but it was just such a joy to see it come to life."
As for the movie’s ongoing appeal, the actor said, "The movie is beautiful and simple and appropriate, and every shot is just right."
Meg Ryan and Billy Crystal pose for the movie "When Harry Met Sally" circa 1989. (Hulton Archive)
In 2019, Crystal reunited with co-star Meg Ryan and director Rob Reiner for a 30th anniversary screening at the Turner Classic Movies Film Festival.
Rob Reiner credits Billy Crystal with "When Harry Met Sally's" most memorable line, "I'll have what she's having." (Gregg DeGuire/FilmMagic)
Crystal stars as Harry Burns opposite Ryan, who plays Sally Albright, in the 1989 movie.