Running gags that turn out to have great meaning

Josuke getting pissed when someone insults his hair-Jojo’s Bizarre Adventure. At first it just seems he’s very defensive about it, but later we learn that when Josuke was young and deathly ill, he and his mother were helped out of a blizzard by someone with the same hair style. Josuke adopted the hair style out of respect for him and sees anyone who insults it as insulting the man who saved his life

Rick’s catchphrase-Rick and Morty. Initially it just sounds like a lot of nonsense and Rick just being his usual self. But later on Morty learns from Birdperson that “Wubba Lubba Dub Dub” actually translates to “I am in great pain, please help me” in his language

Ice King kidnapping princesses-Adventure Time. Initially it’s just the stereotype of evil wizard kidnaps princess to make his bride. But after learning that Ice King was actually driven mad by the crown we see that even in this insane state he is subconsciously trying to find his wife Betty who he lovingly called “his princess”