Best Practical Joke Ever

So my sister just got a tattoo in another language. She calls her husband "pants" (smarty-pants, cutie-pants, etc.) so she got the word "pants" in Latvian tattooed on her arm as a surprise for him for their anniversary. Our family is Latvian but only my mother speaks it, and she is a bit rusty since she does not have anyone to speak Latvian with. The Latvian word for pants is "bikses". I convinced my mom to tell my sister that she talked to our Latvian jeweler friend and told him about her tattoo, and that he informed my mom there are variations on the word bikses, just like we have variations on words like "dear" and "deer", "here" and "hear" and so on. We convinced my sister that the Latvian spelling for pants should be "bixes" with an "x" and what she has, "bikses" means penis. She was mortified! After I told her it was a joke she cursed me out for a good 10 minutes and said she hopes I gain 10 pounds! Luckily I was on the phone with her because if I was with her in person she probably would have killed me.