All the cartoons have a little explanatory paragraph. In this case, a Mike Malone was a notorious cheat. A tourist girl came in for a tattoo, she gave him her name and number, and he wrote it down in hexagram pen while he was drawing her tattoo. One thing led to another, he ended up getting a blow job, and accidentally sitting on the contact info for her while he got it!
For three days his girlfriend gave him the cold shoulder, and when he finally exploded on her, she asked about the backwards contact info for a girl emblazoned on his jeans!