Beck talked about ghetto blasters in one of his songs. So make all the lame jokes you want, you're cool with me for life now.
I do this ALL the time. Well, I may not physically finish the sentences all the time, but I'll have what they're about to say formulated in my head and I'll sort of start nodding in agreement way too early, lol. I'll get all enthusiastic and want to jump right in with my own corresponding point before they're finished making theirs, and so I often have to consciously make myself shut up and focus before I get to the point of feeling that I'm being a nuisance.