Derived from the skateboarding culture, where 'hammer' means a really difficult trick, usually involving some danger. Like busting a trick on a handrail or set of stairs. Lifestyle hammers are the same principle, but involving non-skateboarding situations.
Stormy: oi woody rip that bong bro.
Woody: nahhh dude iv already had like 5 cones.
Stormy: cmon dude it'll be a mad lifestyle hammer
Today I drove manual in traffic while eating a mcchicken meal on the run. It was a mad lifestyle hammer.