I'm not exaggerating or trying to be funny. He really did suggest corrective lenses to help with night-time driving, and he really did say "yo."
Today I saw the hawker rapping again, although I can't be sure that the guy I saw today is the same guy I saw a few months ago, because -- check this out, yo! -- it turns out that numerous Megane Suupaa hawkers at locations across Tokyo are using this atypical sales strategy these days. A quick search of YouTube reveals a treasure trove of videos of rapping hawkers, most of them working at Megane Suupaa. The Akihabara guy even uses a little boombox playing a hiphop beat to help him bust it out fresh, yo! He also uses the "faux gaijin" pronunciation style that is popular with Japanese rappers, who desperately wish they were foreign.