Graduation Photos... how do they do this?

My granddaughter will have her graduation party with 2 other graduates - all friends who have been in school together since Kindergarten. I'm creating the video slideshow for the party... so here is what amazes me.

At the graduation the 3 graduates mimic'd photos they had taken together since birth. So if they were all acting goofy and making faces they did the exact same thing right after graduation. There are MANY such photos. How did they remember those poses from as long as 17 years ago?

It's not that I have not seen this before... Facebook and other social media sites are full of such photos BUT.. it still amazes me.

While I'm at it.... about graduation. I graduated in 1966, from High School. At my graduation I, and nearly every boy in my class, had a pint of whiskey under my gown. I'm not being boastful... that was a dumb thing to do. But it gets even dumber... I didn't drink Whiskey then and never took a single sip of that pint during or after graduation. It was a 'status symbol'. I think back on that now with the realization that WOW.... was I ever a stupid teenager.