Alice in Wonderland the Disney cartoon had one of the most memorable scenes of my childhood, but I think I'd have to go with two from the old Scooby Doo cartoon.
One is from Scooby himself *surprising I know. A male character having one of my personal favorite build ups? INCONCEIVABLE! XD* The sneeze happened in an episode where he is in an old sawmill. Sawdust and dust in general is everywhere, and as he is trying to sniff for clues the way he normally does, sawdust piles up on top of his big nose. I think what made this build up so different from his other sneezes is he desperately tried to hold it back, with him even swishing and wriggling his muzzle to try to shake off the sawdust. It didn't work, and he ended up sneezing a strong sneeze.
The other is from Velma. The mummy episode from Scooby doo is one of my favorites of all time, and this sneeze plays only a part of the reason why. Velma is, don't ask my how, quickly disquised in an Egyptian outfit. Her hat has a long feather that reaches downwards because of her breathing and tickles her nose three seperate times. What gets me in this build up is how you see the Mummy getting closer and hear the tickling sound effect of the feather, but the sneeze doesn't happen yet. It builds up, and she tries to resist starting to hitch her breath for as long as she can. Eventually, however, the tickling feather proves too much for her to handle. She sneezes just at the right moment too, distracting the mummy to turn her way as Scooby escapes the mummy's sights.
Special mention goes to that Pooh sneeze, and also the scene in Fox and the Hound where both foxes sneeze
I loved her sneeze, but what made this sneezing scene memorable to me was how one sneeze from the flower caused the other to sneeze too. I rarely ever see this happen in all my time watching movies and TV.