In "touching tubes", two men touch the tips of their penises together then pull forward enough foreskin so that it covers both their penis heads, so the two penises now look like a single shaft connecting the two men's bodies.
That looks totally trippy-- and it sounds more than a bit romantic!-- but it is all totally no homo, because nobody's balls are touching.
If there's not enough loose foreskin (or just plain shaft skin) to cover both heads at once, then the two men are trying to touch tubes, but not quite managing it. However, that attempt still counts as "tip to tip", and a nice friendly sword fight can be the participation trophy.
Conversely, if there's there's a great deal of foreskin, then the men can even do full-on docking.
Comparing sizes can be a gateway drug to touching tubes-- which can immediately escalate to a non gay handjob, and from there, to anything.
"Me and my entirely platonic friend Kyle were comparing sizes, to address the question of 'grower' versus 'show-er'. Then hey yolo, so we decided to try touching tubes. I don't have much slack, but we did just fine, because he's got a glorious anteater! Then, in the spirit of wholesome friendship, we fell right into a bro job and cum swapping session that lasted for hours. But we wanted to clarify that this is no homo, so later we each gave each other a non gay handjob... several times... just to make sure we're totally straight."
The most intimate thing that two mentally ill people can do. The process is similar to that in Avatar (2009), but with feeding tubes
Dude, let's tube touch.