Chris Finch makes sexual references in all of his appearances, and has sexual intercourse in a short, 10 second end credits scene. Played for laughs.
The "Party" episode often features a dildo, in one scene it is accidentally turned on and it spins around. It is never used in a sexual context. Played for laughs
Season one, episode three ("The Quiz"): someone gets a life-size inflatable penis as a gift, and multiple characters joke about it. This scene lasts for about 30 seconds. Near the end of the episode, it's kicked around by Gareth for a couple of seconds.
Season two, episode one ("Merger"): a slang word for penis is spoken a couple of times in a joke.
Season two, episode six ("Interview"): Gareth puts an adult toy on his desk. The toy is a man that says, "Oh yeah, oh yeah, come on, come on, baby!" in a sing-song manner before music plays. After the music plays, the toy screams out "Oh, oh, oh! Oh, no!" (It's implied that the toy man has a simulated orgasm). This scene lasts for about 30 seconds. Comically shown.
Christmas special, part one: Some discussion of a sexual position. No explicit anatomy names are spoken but lasts for about 20-30 seconds.
A raunchy running joke relates to Tim and Dawn "winding up" Gareth by asking him about his military experiences in thinly-veiled terms for gay sex, with him not realizing it.