Holding a blue Forest Service bag below your asshole and taking a shit, usually done in the far depths of the wilderness to protect the environment and other adventurers' well-being. These are most common in snowy mountain environments where buried poop would become exposed again within a few weeks.
(National Forest Ranger): Thanks for signing into the climbing register! In case you haven't heard, there's no toilet on the mountain this year. Did you pick up some of our waste disposal bags?
(Hiker): You mean the things you take a dump into? Yup...
(Forest Ranger): And you know about our ongoing campaign, right? -- Don't throw the bags into crevasses or pit toilets, carry them (filled with poo) all the way back and throw them in the trash.
Blue bagging is the act of going to the off-licence and getting drunk at home or the park (dependent on age) instead of going to a bar. Often done near the end of the month just before payday when most people have no money. Named blue bagging as the majority of plastic bags from local off-licences are indeed blue.
Steve: hey pete you gonna come out with us tonight.
Pete: no sorry dude im blue bagging with alex tonight.
when you go to buy weed from a guy and he hands u a bag of shit that you cant even tell is weed because its in an opaque blue bag. usualy filled with no buds, bad shake, and shitty regs or very low middies. if u get blue bagged, promptly hand it back and swiftly roundhouse the dealer in the temple, right bi-cuspid, or any vital extremities.
guy one: did u pick up that 1/8th from that sketchy new guy last night.
guy two: nahh son, he blue bagged me and try to sell me a bag of paprika.