As I've already said in a previous post, the Ub Iwerks studio produced during the Thirties some cartoons filled with naughty gags. One of the best examples (and, in my opinion, one of the best Flip cartoons) is "The Office Boy" (1932).
In this cartoon, Flip the Frog gets a job as an office boy (of course...). While doing his work, Flip flirts with a (beautifully animated) secretary who works in the same office. After dancing with her, Flip tries to get rid of a mischievous mouse, with disastrous consequences, and in the end Flip is fired by his boss.
In this naughty pre-Code cartoon, there's space for lots of sexual gags, and in one scene we even see an on-screen toilet.