He wasn’t even on her register

Some college friends were reminiscing, talking about buying condoms from McLanahan’s, a classic Penn State establishment. One of the friend’s little sister was the lone cashier in the store, and the other friend who purchased one was mortified that she sold condoms at that age. Her sister then said, “she sold condoms to half the students at Penn State, so you weren’t even on her register.” This is a congruent conflation of “not on (one’s) radar” and “did not register”, both referring to something or someone not important or noteworthy. There is a pun there as well, as the speaker may have been thinking of a cash register as her little sister was a cashier. A big thanks to Adam Jacob for hearing this one and sending it in.