My personal pet hate no. 1 is Happy Birthday, for several reasons. It is over-repetitious. It has little in the way of a tune. Often it is sung in several keys at once. Often when it gets to the name of the person whose birthday it is, many of the people who have joined in up till then realise that they have no idea who that is so they leave the name out. Sometimes it is even sung after the relevant birthday has passed, when the sentiment "happy birthday" can logically only refer to the next one that is nearly a year away.

When I had a big party for my 60th birthday (actually a few days early), I gave notice that if anyone sang that song I would leave my own party.

The Swedes have one with much more substance but I am sorry to say I don't know that one.