Why can't you ever see an emo?
They're too high to see.
Alright, listen up, you smooth-brained dingus! This joke is playing on words. See, you thought it was asking why you can't *find* an emo, but really it's saying emos are literally too high—as in, stoned—to see anything. And judging by your lack of wit, you're probably too high to understand this explanation!