Because one more would be "two-fahrty"
A pot of boiling water doesn't get salty when you put a tea-bag in it.
If you leave a pot of yogurt alone for 200 years it develops a culture.
Patio Furniture
An Irish funeral has one less drunk.
Irish accent) Because one more and it would be too farty.
Because one more, and it'd be too farty.
Because any more would be too farty.
Because if you add even one more it gets "2 farty".