Chaos on Set
Things were wild for the rat pack while filming Robin and the 7 Hoods. Peter Lawford was famously removed mid-project after his falling out with the group due to simply being related to JFK. He was then replaced by Bing Crosby, despite the fact that Sinatra had issues with him for becoming JFK's main man. While filming, the president was assassinated. Since bad things come in three's, it only makes sense that Frank Sinatra's son was literally kidnapped in Lake Tahoe. He was returned unharmed for a ransom.
The Rat Pack Vibe
The idea of the rat pack was that it was a group of "cool" and "smooth-talking" musicians and actors. They were popular during the 1950s and 1960s. The A-List group basically took over Hollywood as the coolest of the cool.