Serious cursing, with no underlying spirit of fun, includes expressions such as yemakh shmoy, “may his name be blotted out”, a phrase as deadly serious as Yiddish gets. It isn't cute or funny or terribly memorable in translation; it isn't an insult or an expression of distaste or impatience. It's a real curse, and seeks to put an end to its object.
It takes us right back to the realism at the heart of so much Jewish religious thought; blotting out a person's name is the same as blotting out that person's existence. To forget a name is one thing; to efface it completely is to efface its bearer from the Book of Life as well as the Book of Those Who Have Lived. Yemakh shmoy ve-zikhroy, a fuller version of the same thing, "may his name and his memory be blotted out,” makes this abundantly clear: there should be no memory of this person's existence--no children, no grandchildren, nothing.
Just as nasty but somewhat more oblique, opkoyfn zol men im baym tatn zayne malbushim, "may his wardrobe be purchased from his father,” is so vicious that it could easily backfire and make the curser look bad: when you wish a person dead, you're not supposed to calculate the consequences.
Below are some items for sale from eBay for those of you with an interest in Yiddish.