Usually taking place on Facebook, when one posts a comment on something and another person replies to that comment creating a conversation via commenting instead of simply using chat.
1: "This picture is great"
2: "Ya i remember this"
1: "You weren't there"
2: "Uh ya i was, i just wasn't in the pic"
1: "Prove it"
2: "I don't have to prove anything to you"
3: "chill guys this is becoming a Comment Convo. Take it elsewhere."
A conversation that takes place on facebook between two people, online at the same time, that comment on each other walls instead of using the chat feature.
John: "I got so many notifications on my facebook due to your comment convo with Jane"