"Hahaha, guys, that was so funny...you duct-taped Buzz to the flight simulator upside down, good job." Deke Slayton, Alan Shepard, Jim Lovell, and Wally Schirra
This picture probably dates around 1963. Three Mercury 7 vets - Slayton, Shepard, and Schirra - look like they're sharing a joke with then-rookie Jim Lovell. My (hopeful) guess is that they were actively hazing the new class of astronauts coming in.