"Gathering roots" is a secret bro code that bros can use when they know their roommates need to totally crush some puss. This is a smooth way to get some privacy without having to make it awkward in front of your chick.
Example: "You know uhhh, there's some more roots I wanted to get.. on the other side of the mountain. I shall go and get them now."Note: Even if privacy is not an issue, this can still be used to avoid listening to the shrill, annoying sounds that awful woman makes while your bro lays pipe.