The Tribulations of August Barton by Jennifer LeBlanc

August Barton could never have mentally prepared himself for his freshman year of college: not only has his anxiety increased, but his parents are divorcing, his new roommate thinks Augie is the biggest nerd in existence, and his grandma, a retired prostitute named Gertie, has taken to running away from her nursing home. Augie just wants to hole up in his dorm room with his Star Wars collectables and textbooks, but Gertie is not about to let that happen. What ensues is a crazy ride including naked trespassing, befriending a local biker gang, and maybe-just maybe-with Augie defeating his anxiety and actually getting the girl.