My office is down the street from a high school. I get to see a lot of kids walk by to include the scary-sensetive, don't-look-at-me-even-though-I-dress-to-be-noticed "emo" types. Curiously, I have never seen a fully actualized serious adult emo. Apparently emo is a phase.
Every since I heard of emo kids, I have mentally cross-referenced them with Elmo (their polar opposite). Elmo is bright, cheery, and fun. Emo kids are typically in a dark mood and seem obsessed with pain and sorrow. There are some similarities though, both are gender-ambiguous. Well, that's about it.
Tickle Me Emo, then, would be a dark, brooding Elmo-like figure. Your emo-kid would squeeze and tickle him to hear dark poetry in morose tones, such as Edgar Allen Poe's Alone. Poke and prod enough and Emo gives a spastic, fitful response with crying and screaming.
Before I post an idea, I like to search it online and see if anyone else has done it before. I should not have been suprised to see that Mad TV did a take on Tickle Me Emo in December of 2006. It's funny stuff, but I don't know that I would want to explain it to small children:
