drive by conversation 

Usually happens on an instant messenger. A person will quickly sign on, leave you a rude remark, and then sign off before you have the chance to respond. It'd be harder to do in a person to person conversation because you could easily kill them.

computer message SoAndSo123 has signed on
SoAndSo123: You're gay
computer message SoAndSo123 has signed off
Me: Damn I've just been in a drive by conversation!

drive by conversation by Cerpin Taxxt February 2, 2007

Drive-By Conversation

When you are walking past two or more people having a conversation, and not knowing the context, often perceive it as inappropriate or funny.

(Man walks by)

Guy 1: Yeah she's really taking it hard.

Guy2: yeah it sounds like all that vibration is killing her bones.

Man 1: That's a drive-by conversation if I ever seen one.

Drive-By Conversation by Caseyds620 January 25, 2011