stoner tangent
The out-of-nowhere tangent subject that comes up in the middle of a conversation between a group of people who smoke weed a lot.
Stoner 1: "So, last night was fun. I got really drunk."

Stoner 2: "Yeah. Do you ever think about what it would be like to be a duck?"

Stoner 1: "Dude. That was a total stoner tangent."