Hang loose like the balls of a moose
My informant learned this expression at Carroll College in Wisconsin. People said the phrase when they were going to go out to party. Sometimes hang loose can mean to relax, but in this context is was to let down your barriers and party hard. This was a common expression among the students especially on weekends. My informant has not used the phrase very often since college as my informant said it was more of a youthful expression.
This expression could have come into existence as a result of two cultures combing. The vulgarity of it and the sentiment came from a college environment where people were encouraged to party and drink, especially as the drinking at was 18 in Wisconsin at the time. The “ball of a moose” part came from being in Wisconsin where moose sightings would have been much more common than in other states like California or even Illinois where my informant was from. The balls moose are evidently very loose and it fit well in the area combined with the demographic the saying appealed to.