It's a casual way to ask someone what they're up to, especially if they're not doing much. It implies a sense of boredom or inactivity.
Here are some scenarios where you might hear this phrase:
* Friends chatting online:
* "Nada fomando y tu?" (Nothing happening and you?)
* "Igual, solo viendo Netflix." (Same here, just watching Netflix.)
* Two people meeting randomly:
* "Hola! Nada fomando y tu?" (Hi! Nothing happening and you?)
* "No, nada, solo caminando." (No, nothing, just walking.)
Essentially, it's a playful way to express: "What's going on? Anything interesting happening?"