I'm a kid at heart and did find this amusing. Very simple to do on a laptop, desktop or tablet so thought I'd put it together (on the train to keep me entertained).
Basically you can do these in a few minutes and send them to your friends or put them on social media with a "really hot at the beach/pool today" comment...Wait for the responses and then send the updated "original".
Here's how you do it....
Step 1: Background Selection
Bring up a full screen image of a beach, pool setting of somewhere very luxurious. Now position you index and middle finger so they are bent like a pair of legs with "knees" up in the air and hover in front of the image getting as much light to the fingers so as not to silhouette them.
Take the picture with the other spare hand and make sure the "legs" are at the bottom of the image.
Step 2: Quick Edit
Now, go to edit image and play around with the lighting/filters until you're happy that the both the background and foreground marry up and doesn't look too fake. Trim the image so just the beach is showing around your "legs" and there you have it. Now go off and make your own images to confuse your family & friends!