Bitstrips is a Facebook application. It lets users create customized cartoon characters and publish single-cell cartoons. It also allows you to "Put your friends in hilarious comics where anything can happen."
Unfortuantely, the art and illustration is infuriatingly ugly. Valleywag called Bitstrips "universally hated." As an Old Person, you get a pass on bad Facebook apps. You earned your Oldness and can do whatever you want!
For instructions on how to block Bitstrips (with gifs!), see this lesson from Buzzfeed. Beware: I often see users upload their Bitstrip as an image, which circumvents the app. (Therefore, if I had blocked the app, I'd see it anyway.)
So now you know what all those weird, funny pictures are!
How To Block Bitstrips From Your Facebook Timeline, Buzzfeed
Bistrips, Universally Hated Facebook Spam Company, Bags $3 Million, Valleywag