"Nah Dougie, I'm going over to Canadian Tire to check out radiator hoses, eh"
They either choose to, are force to, or symply end up proceeding alone on a mission that shows very little likleyhood of a non-negative outcome.
"Johnny went on some kind of Solo-Act last night and ended up in jail."
"Fuck it! If nobody wants to roll with me, I'll do a Solo-Act! Then I don't have to split the money!"