It's funny, because I really can't remember anything about it, but I am 100% positive that the first cartoon tickling I can remember seeing as a small child was on the Jetsons. A lot of scenes occurred over the years, of course, but they tend to get fuzzy in memory, with rare exceptions, the biggest of which may be, because it was the focus of the whole episode and not just a scene, the Underdog four-parter in which Simon bar Sinister tried to get elected mayor by creating special tickle feathers to keep everyone but himself and Cad from voting. It seemed so nicely plotted - testing Cad to see what could keep someone from voting and discovering tickling worked best, trying out tickle feathers on a chef, an executive and other guinea pigs, then making a huge supply and seeding clouds with them so that Election Day dawned to find a swarm of tickle feathers raining down on Metropolis and tickling the entire population into helpless hysterics while Simon and Cad cast their votes, the showdown with Underdog and Sweet Polly Purebred during which, even Underdog succumbed to the might of a tickle feather (for a while at least, though he was able to cast his own vote), and even the useful civics lesson in Underdog's eventual loophole that Simon's and Cad's votes were illegal because they were never registered (and the obligatory retribution at the end when Simon went to fire another tickle feather at Underdog only for the barrel of his tickle feather gun to turn back and fire the feather at himself).
For a scene that was just a scene, it's very sad that there's one which may never be seen again for reasons of political correctness. There are two versions of a Porky Pig cartoon - one called Wagon Heels and the other Injun Trouble. I'm not sure which it was I actually saw. PP was a pioneer going west, despite the news that the wild Injun Joe was wreaking havoc in the territory and ought to be avoided. PP pushed bravely on, though, continually meeting up with a hillbilly singing, "I know something I won't tell," to the tune of London Bridge - very irritating. Eventually the intrepid Porky runs into the troublemaking Injun Joe, who soon has him cornered and is about to do him some grievous bodily harm when the hillbilly pops up again, revealing that what he knows is a secret about Injun Joe, who of course towers over him, conqueror over all Man, Beast and Nature as far as the eye could see, backing him to the edge of a cliff and demanding to be told the big secret. This of course leads right into the classic line, "Injun... Joe... is... TICKLISH!!!" as the hillbilly tickles the conveniently barechested Injun Joe into instant hysterics - on the ground, falling off the cliff, swinging into midair until, after Injun Joe flails about in midair for several seconds being tickled by the hillbilly's fully extended twenty-foot-long beard, he lands back on earth trapped in a hollow tree, where his now-bare feet, torso and other ticklish spots keep sticking conveniently out of the hollow limbs as he squirms wildly and helplessly about, still laughing maniacally as the hillbilly keeps tickling him into the screen starting to fade out to credits when Injun Joe bellows either STOP!!! or WAIT!!! When the picture is restored we get the absolute killer, Injun Joe pleading, "Do-um more!" and being tickled again to his evident delight as the scene fades out. Just seeing a cahracter so apparently invulnerable to anything being so instantly and completely overpowered, and reveling in it, made an incredibly strong impression.