I made a point to locate the Comcast poster (discussed below) on the way to work today.
I have to correct myself. It does, in fact, say "TENDERNOB" in all caps, with no "K".
Chalk it up to my poor eyesight, I suppose.
The poster in question is located pretty much in front of the Orpheum (between Seventh and Eighth Streets, on the north side of Market).
[UPDATE 5/3: And, as it turns out, there's also one on the corner of Market and Noe in front of the gym, just opposite the F-Market stop.]