A phrase used between two people who know it to tell one another when they need to take a shit. It is only used in the presence of people who you don't want to know that you have to take a shit. You can add adjectives to this phrase to describe the current situation. See below
Normal - "Hey dude, I gotta go catch a train, I'll see you later"

One that is about to come out - "Brady, I just remembered that I have to catch a train with my brother, and I'm runnin way late. I gotta run!"
by C - Dub - Weekly September 1, 2008
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The coolest new thing on social networking sites, concerning hacked accounts.
Asker: Hey there, did you catch the train?

Answerer: wait.. what? train? did someone hack my account?

Asker: ahah hahah hah hahaaa
by PuhblikTrahnspohrtashun May 15, 2009
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To participate in smoking some marijuana with some friends. Preferably smoking a blunt, which is sometimes referred to as an L.
Hey James, are you trying to catch the L train with me and Iulian later?
by GMon$y December 16, 2012
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