P3X-595 was a planet in the Milky Way galaxy that SG-1 visited prior to the mission where they encountered the Shavadai. After having been saved from Turghan, Samantha Carter said that she had never been so pleased to see the rest of the team. Jack O'Neill replied by referencing a mission to P3X-595 where Carter drank something that apparently caused her to take some, or maybe even all, of her clothes off. Carter interrupted O'Neill before he could reveal any more details of the incident. (SG1: "Emancipation")
Behind the Scenes
Fans, especially "Jack/Sam" shippers, often speculate as to the specifics of what happened on this planet. It is often a subject of fan fiction and there are at least two fan websites named after it.
Sam: What a relief. I have never been so happy tp see you guys .
Jack: Oh, sure you have ! Remember that time on P3X-595 ?! You drank that stuff that made you take off …
Sam: ...Ahem . We won't get into that now .