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5.
the day after national marijuana smoking day, the national pixie stick snorting day was established last year by Brandy and Emma.
shit bitchits 4/21, ima empty this pixie stick up my nose and snort it in the middle of the road while trying not to get my nigga ass run over.
by Emma and Brandy October 13, 2007
 
1.
The day after National Marijuana Day. Also known for parents as National Drug Test day.
Billy: I'm going to smoke a shitload of pot on 4/20!

Bob: Your parents are psycho. I'm sure they are gonna make you piss in a cup on 4/21.
by Fuzzy Pinata April 20, 2010
 
2.
When you forget to get weed for the actual 4/20, and can't find any because everyone is using theirs, or you are otherwise unable to celebrate on the actual day. So you therefore celebrate the day after...4/21
Sarah: Hey, do you have any weed?

Megan: No, and I can't find any from anyone else!

Sarah: Damn... 4/21?
by classy pseudonym April 20, 2010
 
3.
national burnout day
man, dont make me do anything, its 4/21 im to burnt out
by krisssssssssssssssss April 28, 2007
 
4.
Used to describe a hangover from marijuana.
"What's up with you man?"
"Nothin, I'm just totally 4/21 right now"
by Mr. Washable October 17, 2008
 
6.
An epic hangover
4/20: amazing day where everyone is hella fucked up all day.
4/21: the day after when everyone is too hungover to do anything and wishes it was 4/20 again
by prettylittleurbanprincess April 22, 2011