I'm shy, in a peculiar kind of way, about communicating with people I don't know. There's a threshold, and only certain situations will get me over that threshold. If I have something I know to say, for instance, and I can convince myself it's relevant to the conversation, I can usually open my mouth. That's rare, though, and tough, and I'm afraid in my efforts to improve my social skills I may have somewhat degraded my criteria for relevance.
Another behavior which I often exhibit is what I call the meme grenade. I do this both in person and online. I'll toss an utterance of a few words into the group, carefully constructed to catch in people's heads and stimulate thought and conversation. Often, I'll then withdraw a bit, since the grenade was all I had to offer. More often than not, it's a dud, but it goes off frequently enough that I get reinforced for doing it. There's a little bit of glee I derive when, for instance, a thread or subthread discussion I initiate snowballs into a weeklong conversation.
There's a little subvocal exclamation in my head when I pull the pin. Translated to words, it might be, "Fire in the hole!"
I'm a visual person. There's a part of me that attributes synchronicity or something to the faint resemblance between an old-fashioned pineapple grenade and the capsid of a virus.