One of the kids in my extended family mispronounced truck for a good 6-8 months. His parents did everything to try to break it. He would consistently run around yelling FUCK RRROOOOMMM (truck sounds) FUCKKKKKKK. Or mumbling in the corner "fuh fuck. fukk goes roooom. fuck. fuck" For a bit, they thought he was doing it because it got him attention / inspired laughter. They would let everyone around know about it and ask that we didn't laugh out loud or give it attention and to simply ignore it. Trying not to laugh only made us want to laugh more.
Had an ex-girlfriend. Her family was kind of annoying. She had a half-sister about 18 months old. Her grandma drove a volvo. Little girl pointed out the window at grandma's car and looked up to me. "Volvo," I said. "Vulva?" She said. "Close enough," I said. Kid called cars vulvas for the next six months. Ran around the house going "vulva vulva vulva!"