EWWWWW and other first words.

So....my son has learned a few words. When I say a few I mean about 5. His first word was maama which turns to mommy when he is really sad. Next came uh oh buguio (uh oh spagettios.) What was hard with that on is that he quickly learned when he dropped something he should say uh oh. We all praised him for learning the word. That is until he began dropping everything over and over just to say uh oh...woosh there go the cheerios UH BUGUGIO...cup UH OH BUGUGIO.....spoon and so on. This was then followed by ITTY which means kitty. However his newest one is the worst of all. Recently he had a poopy diaper and he was pretty upset that I wouldn't let him sit in it all day. So in an effort to calm him I started pretending to plug my nose and say EWWW. He thought this was hilarious. So started the game. I would change him and say Ewww about 50 times and he would just giggle on. Then he started repeating it. I was so impressed with him that I laughed along. Heres the problem. He now thinks that when you say eww its funny to continue what he was doing. So today we are in the bathroom and he picks up his booger sucker, sticks it in his mouth and starts sucking on it. I shriek EWWWWWW with a serious look on my face. He breaks out in a fit of giggles starts repeating EWWWWW and since he thinks he is so cute he continues sucking the boogers out. After I swallowed the vomit back down and managed to get the booger sucker away I realized I'm in for trouble now. I guess I'll have to start saying yucky and try and get him to see that yucky means bad.