Asking someone you meet “How are you?” is etiquette but they also expect a good response from the other person. You can respond to them in many ways but it depends on what kind of relationship you have with them. If they are a colleague or a stranger, reply with a smile and a positive tone. You can use phrases like “I’m great and how are you?” Ask them the same and maybe have a small talk if an interesting topic comes up.
Funny or witty responses are more ideal for people you have a more casual relationship with. Friends, classmates would find these answers funny and would take it lightly. Furthermore, responding with a simple “I’m fine” can be overkill. Send a meme or something like “I was fine until you asked” or “It’s a secret.” These are great for lightening the mood and we all like to laugh on our misery. Don’t we?