Why is it necessary to use mushrooms when you pee in Death Stranding?
Urinating is one of many things that Sam does, for this we will have to make use of the D-Pad, right, keep pressing L1, before holding down R2, and obviously this liquid contains fungi called chirograms, to get them in need to urinate too much.
Once Sam urinates in the bathroom there will be a mushroom, it is small, which seems insignificant and harmless, only after a while it has grown, these shows us groups of two to three people, in a moderately long period of time. This is all we have observed so far, they might have some other effect in the future.
To close knowing how to use mushrooms when you pee is not entirely clear, since we must wait to see how everything progresses in Death Stranding.