Pipes are a common obstacle and method of transportation in the Mario universe. Some pipes often lead to various places, in which Mario can enter. As SuperMarioGlitchy4's videos are mostly based on the video game Super Mario 64 on the Nintendo 64, several pipes appear sometimes in his videos. They're usually inanimate objects, but in the blooper "Problematic Pipe Problems", they appear as living characters, and they have a chief called King Pipe.
The pipes exist in several colours, but the most common one is green. The sentient pipes look exactly like the other ones, and are faceless despite being living characters. However, one of them was seen wearing glasses.
Appearances in SMG4's videos
Pipes appeared in many bloopers of SMG4, but "Problematic Pipe Problems" is the only video in which they appear as living characters, and it's their first and most prominent appearance.