I just remembered something from a story about a bunch of guys that got Delta P'd halfway through an oil pipe. They had to "Pig" the guys that didn't make it out the other end of the line.
>But anon-kyun <3, what's that mean?
So glad you didn't ask. When talking about pipelines a "pig" is a projectile that is fired down the bore or the pipeline for any number of purposes. Some are for cleaning or scraping, some have instrumentation on them for diagnosing all sorts of things in the pipeline. They are launched at pretty high velocities.

Now imagine you are valiant mobik sent on dangerous mission through enemy pipeline for glorious motherland! Imagine you are halfway down and suddenly you feel the air in the pipe start rushing back the way you came fast. If you are not thrown back by the gale the last thing you see is pic related zooming at you as it "cleans" you and your friends out of the pipe.

Now imagine being a guard on the Russian end. Workers say a pig came through, you being mighty mobik of pig slaying you run to pipe with gun ready. When you get there you find there are no Ukrainians, just some weird object and some sludg... IS THAT OF BEING SERGEI'S LUCKY HAT?! CYKA BLYAT! Sludge is of being PEOPLE!!!

There are so many ways you can be killed absolutely brutally in those pipelines if anyone ever tells you to go down them you should probably shoot that guy instead.