Wednesday is April 20, better known as 4/20. It's considered a major holiday to those who smoke marijuana.
About twenty percent of those who attend the event are University of Colorado students. This week, school administrators sent them an email asking them not to attend the event.
"It's certainly not an event that we welcome," Bronson Hilliard, a CU spokesperson, said. "We've messaged our students that it's not a good place for them to be. It certainly is not a sanctioned university activity".
Last year, seven students were ticketed during the event. Hilliard says some students could be expelled if they get out of hand.
"If you're walking across campus lighting up a joint, you're going to get a ticket," Hilliard said.
"I think it can be interesting," Rhonda Horton, a CU student, said. "Some people see it as a protest and other people see it as an excuse to smoke up in public".
About a week ago, Playboy Magazine named CU the number one party school in America. Playboy cited the 4/20 smokeout as one of CU's charms.
CU says it's difficult for a couple dozen officers to manage the large crowds that emerge on 4/20.
Officers can't arrest anyone who is carrying less than two ounces of marijuana, but they can issue tickets.
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