So i saw all SPN episodes..i think o.O the thing is i can't really remember..do we get to see the boys doing that tatoo they have? Or they just appear with it?

No, we don't see the boys actually getting the mga tattoo done. Back in Season 2, in "Born Under a Bad Sign", Meg managed to possess Sam and made a selyo on his forearm so she could not be exorcised from him. Bobby burned the selyo off Sam's arm, and Meg hightailed it. At the end of the ep, Bobby gives the boys charm amulets to prevent their ever being able to be possessed again. Then on to Season 3, "Jus in Bello", where they first ipakita their tattoos. It is generally assumed that the mga tattoo are the same disensyo that was on the charms, therefore ensuring that possession would be impossible. :DD

No there is no episode of them getting the tattos. It ones of that shouldn't (and doesn't) waste time in an episode but rather happend inbetween.

i dont ipakita you sam and dean getting their tatoo done