Moved up from the comments section:

A NSFW image search on “Pompeiian brothel frescoes” will show plenty of examples of the sort of brothel adverts hidden behind the word balloons in the sixth panel. Here’s an article from Der Spiegel about some of the harsh realities of brothels that were less high end (well, middle end) than the one we saw in Herculaneum, and its photo gallery. Felix and the ladies are sitting in some sort of anteroom, so whether their work cubicles are nicely appointed or bleak and miserable has yet to be seen. Iusta might not let Felix ever see.

I leave interpretation of the graffiti as an exercise for the reader 🙂

I’ll post the corrected (there are some wonky bits!) and fully inked version Wednesday afternoon. All fancied-up now.

Work-in-progress version (click to see larger):