“may your intestines be pulled out of your belly and wound around your neck”
“may i have the privilege of sewing your burial shroud” also “i hope your enemies break their ankles dancing on your grave” (and another, in a similar vein “May you turn into a blintz, and your enemy into a cat, so he should eat you and choke and we should be rid of you both.”)
and of course this one:
(now, in exchange, can i have more irish curses please?