What would you do if you were in some random parking lot—Lowe's, let's say—and all of a sudden dozens of car alarms started going off at once? Would you shrug it off like the dead-to-everything city dweller you are? Maybe duck and run and wet yourself because Galactus is obviously coming to devour our planet? Improv Everywhere found out when it pulled the prank for the Guggenheim this past week. The verdict? Fun! But harder to turn off than you'd think.