This is a prime example of a comic that makes me LOL because it catches me off guard. It’s ridiculously funny—and the fact that you don’t get it probably means you are very intelligent...just so you know. ;)
Anyhoo, to put it simply, he reads the word “BOO” and becomes startled. Haha.
I have upvoted some of your memes for having the confidence to ask questions! (I love the concept of a yearbook as a meme, and of course, the sketchbook drawing. I lurve artists!)