The 51st annual Chicago Air & Water Show hits downtown (we hope figuratively) on Saturday and Sunday from 10 AM to 4 PM. Reduced to two days from last year’s three, the annual spectacle/military recruitment stunt features everything from bi-planes to Thunderbirds. Unlike G.I. Joe, it’s completely free. The action takes place over Lake Michigan and can be seen from Fullerton to Oak Street. Expect crowds; an average of 2.2 million spectators are shocked and awed every year.