In this clip from "I Taw a Putty Tat" (Friz Freleng, 1948), Sylvester disguises himself as a Swedish maid in an attempt to snatch Tweety from his birdcage. Tweety fools him with a firecracker, which explodes. When shown on TV in the past, the gag ended there...but in this original, uncut version, Sylvester utters an undeniably funny line in "blackface".
Warner Bros. cartoons often included unique title cards and title animation sequences with animation and paintings of the featured characters. These were often edited out of theatrical reissues and TV reruns, but thanks to proper film restoration for DVD in recent years, some that were previously "lost" have been reinstated, and others we're familiar with are just fun to look at. Here's a gallery of some of them, just for fun!