Not to be rude, this is just a small thing I find annoying.
I have no problem being the one to message first. So when I do, please do NOT respond with "cool". That is so annoying and makes you sound incredibly boring. I won't contribute to a conversation if I'm the only one contributing. I understand if you did it without noticing mid conversation but when I start a conversation and you aren't interested just say "Sorry Kidd" and I'll get the message but don't make me jump through hoops for a empty conversation because then I lose interest in even getting to know you.
I wouldn't have posted this if this only happened once but very often I'll come across people like that. People who say "cool" for every message and then leave the conversation.