1) When something is unbelievable, out of the ordinary.
2) When something is good, excellent, brilliant.
"This is heavy duty Doc!!"
The term "heavy" was said by Marty in all 3 Back to the Future movies.
2. (adj.) Serious and intense.
3. (adj.) Hardcore, brutal, raw.
4. (noun) A tough guy.
5. (adj.) Carrying a weapon, most likely a gun.
Jane: Yeah, I know, he was really heavy.
John: Last night, my mom died.
Steve: Man, that's heavy.
Whitechapel is heavy.
The club was having problems with riff-raff, so they hired a couple heavies to bounce.
The other side came heavy to the fight, so we beat it outta there pretty quick.