How To...Say What You Mean

Lately I find that more and more people seem to be talking just to get attention, or to start a conversation without explicitly showing that they want a conversation to start. This irks me; if you want to start a conversation with someone, just say, "Oh, I was meaning to tell you..." or "Guess what!" or "Do you have a minute?" Because when you just start talking and wait for the appropriate person to join in and say exactly what you want them to say, it's inefficient, and it may not even yield the desired result! I'll give you an example...

WRONG WAY:
Person A: Gosh, I really shouldn't eat this entire sheet cake.
(pause)
Person A: GOSH, I REALLY SHOULDN'T EAT THIS ENTIRE SHEET CAKE.
(pause)
Person A: GOSH I REALLY SH-
Person B: Oh, are you on a diet?
Person A: Yeah. It's this new diet I saw on TV...

RIGHT WAY:
Person A: Gosh, I really shouldn't eat this entire sheet cake.
(pause)
Person A: GOSH, I REALLY SHOULDN'T EAT THIS ENTIRE SHEET CAKE.
(pause)
Person A: GOSH I REALLY SHOULDN'T EAT THIS ENTIRE SHEET CAKE!
(pause)
Person A: GOSH I REALLY SH-
Person B: (shoots Person A in the head)