I.2.20 (Bar/Brothel of Innulus and Papilio); 3932: Weep, you girls. My penis has given you up. Now it penetrates men’s behinds. Goodbye, wondrous femininity!
I.2.23 (peristyle of the Tavern of Verecundus); 3951: Restitutus says: “Restituta, take off your tunic, please, and show us your hairy privates”.
I.4.5 (House of the Citharist; below a drawing of a man with a large nose); 2375: Amplicatus, I know that Icarus is buggering you. Salvius wrote this.
I.7.1 (in the vestibule of the House of Cuspius Pansa); 8075: The finances officer of the emperor Nero says this food is poison
I.7.8 (bar; left of the door); 8162: We two dear men, friends forever, were here. If you want to know our names, they are Gaius and Aulus.
I.10.2-3 (Bar of Prima); 8258, 8259: The story of Successus, Severus and Iris is played out on the walls of a bar: [Severus]: “Successus, a weaver, loves the innkeeper’s slave girl named Iris. She, however, does not love him. Still, he begs her to have pity on him. His rival wrote this. Goodbye.”. [Answer by Successus]: “Envious one, why do you get in the way. Submit to a handsomer man and one who is being treated very wrongly and good looking.” [Answer by Severus]: “I have spoken. I have written all there is to say. You love Iris, but she does not love you.”
II.3.10 (Pottery Shop or Bar of Nicanor; right of the door); 10070: Lesbianus, you defecate and you write, ‘Hello, everyone!’
http://www.pompeiana.org/Resources/Ancient/Graffiti%20from%20Pompeii.htm 
