Shit the bag

To majorly fuck up something of consequence.

Similar to the idea behind "don't cry over spilled milk", this phrase is widely useful. In a situation where something sucks for person A, person B might have the feeling like, well what are you gonna do, you cant do anything, so get over it, as in shit in a bag, man, there's nothing you can do about it. Thus, person B would say, shit in bags.
Props to Jen Smith, of Chicago, IL.

When the toilet is so backed up from your roomate taking giant brick shits that you are forced to shit in a plastic grocery bag and throw it into your roomates room

a useless fuck. Normally a co-worker who does not pull their weight nearly enough. They tend to drove in packs in the military, ie: navy

An expression to describe frustration with an idea or a situation that is equivalent to needing to taking a shit without a toilet.

An individual who smells like hot garbage, bathes in his or her own urine & lives under a freeway overpass; A subject who is usually addicted to one or more drugs. A derogitory comment usually aimed @ transients, crackheads, or asshole buddies.

As the name suggests, a 'shit bag' is simply a bag filled with shit. Alternatively, Wikipedia states that a 'shit bag' is a colostomy bag, but each to their own.