It seems that some “bus friends” are friendlier than others. From Dan in Bellevue*:

Thought I should mention that a “bus buddy” is not the same as a “bus friend” as I found out a couple years ago. I had gotten on a bus on a rainy day riding through south Seattle (the 174 I think) and had on my black bicycle rain pants. A guy who I presumed was mentally challenged got on and sat down in the seat in front of me. He glanced over his shoulder a few times, and eventually asked me if I would be his “bus friend.” Well, there seemed no harm in that so I said OK. So he moved to the seat next to me. I thought we were about to have a conversation, but then I felt a hand on my knee. [After I corrected him, he said] “Sorry,” …but didn’t get up from the seat. … I realized I may have just gotten a taste of what women go through when they get hit on. In any case, I resolved to wear my rain pants less often.

* I removed some of Dan’s dialogue, but I think (I hope) I stayed true to his point.

Also…

In case I didn’t make it clear in my original definition, “trife” is not solely used to describe insane behavior on buses; it has many transit applications. For example, it is often used to describe people who are routinely late for the bus (and the behavior that causes them to be routinely late for the bus). This behavior can be unintentional (the result of oversleeping or underestimating time needs) or intentional (relying on the lateness of buses to plan one’s schedule**). The next time you are late to work for one of these reasons, don’t bother to offer a long explanation. Just say, “I was trife this morning and missed the bus.” Or, if you’d prefer to use the word as a noun: “Trife caused me to miss the bus.”

**One day I dedicate an entire post to this phenomenon.