It's much like the word "crazy" but way cooler. It has many meanings. It can be used as both an adjective, verb, or noun.
Crazyguy is a very active word, full of or characterized by activity.
Crazyguy synonyms are: crooked, askew, mad, insane, impractical, erratic, being
out of the ordinary, unusual,
distracted with desire or excitement,
passionate.
You can use crazyguy in both a good and bad way.
Good:
"Wow, you really made that part in the song so AWESOME."
"Yea, I kind of went all crazyguy on it."
Bad:
"Man,
Christina Aguilera really butchered the
National Anthem at
the Super Bowl this year. She just got way too crazyguy on it."
Noun:
"I wouldn't walk by yourself around here. There's way too many crazyguys in the area."