The transcendental effects of psilocybin mushrooms can improve interpersonal relationships between users.
A shroommate is a person with whom you now have an honest, clear, warm or spiritual relationship, solely because you took magic mushrooms together and experienced the mystical effects together.
Dan: You guys invited Larry yesterday?? Wasn't he awkward?
George: No, man... He was at first, but then we all took shrooms and had a great time. Larry and I talked for hours. We're total shroommates now.
Not to be confused with roommate, a shroommate is one who you share your shrooms and trip balls with. Often times college students are in fact shroommates with their roommate.
Student: You study for the exam today Jeff?
Jeff: Nah man I just did shrooms with my shroommate, we were gonna get some munchies at the vending machine but a pregnant latina unicorn was there so we bailed.