代々墓 (だいだいばか): An ancestral grave
One of my Japanese teachers pointed out that it's often used in sentences like OO家族代々墓, which makes it sound like " the OO family are massive idiots.
I also thought 五十五 sounded funny when I first learned it, because I thought it was supposed to be pronounced like "go Jew go".
It probably doesn't make any sense noq considering how quickly internet language changes, but I learned the word for ambulance (救急車 きゅうきゅうしゃ) around 15 years ago, and at the time QQ meant crying, and was used to call people emotional crybabies. It reminded of the term "wahmbulance" which people would use when someone is being whiny.