Well, it’s not completely certain, of course - and a gladiator would definitely be a prime suspect for such euphemisms - but most of the crude graffiti around Pompeii tends to be… clear about its subject matter.
“Theophilus, don’t perform oral sex on girls against the city wall like a dog”
“Secundus defecated here” three times on one wall.
“I screwed the barmaid”
“Defecator, may everything turn out okay so that you can leave this place”
And incredibly banal subject matter is found elsewhere in Pompeii graffiti
“Aufidius was here. Goodbye”
“Staphylus was here with Quieta.”
“Anteros wrote this.”
“Epaphra, give the paint-brush back”
“O walls, you have held up so much tedious graffiti that I am amazed that you have not already collapsed in ruin.”
I tend to believe it’s just what it looks like - just some bored gladiator celebrating making bread one day!