There’s a few people keeping the practice alive, like Global Penfriends and etc. I don’t know how many choose to use snail mail for it, but I know of people who for various reason enjoy physical correspondence. Probably most pen pals are using email these days – although that’s getting a little archaic now, too!
I have elderly relatives an ocean away from me and they absolutely refuse to text, so we talk via email. It’s kind of like having a pen pal, sort of.
The central premise behind the comic strip is that Dracula, notorious, bloodthirsty villain of novel, film and legend, scourge of Transylvania, evil incarnate, servant of Satan, is also, in fact, someone’s embarrassing, dad-joke loving father, who uses his incredible powers to entertain his son, who is often unimpressed with the results. The point being, it doesn’t matter who you dad is, they are probably a little uncool – even if they happen to be Dracula.
You may not find it funny. Many don’t, and that’s okay. You can’t be “wrong” about not liking something.
The man is trying to make his audience laugh by allowing himself to be drenched in manure. But he is sad because he is being drenched with manure. While this is the main point of the comic strip, whether or not one finds it humorous or tragic is entirely subjective.