Packet and Tripe is a real Limerick city dish. Tripe is the lining of the cow's stomach (whitish), and packet (blue-blackish) is a sort of pigs blood pudding. It is very easily digested.
It is no longer prepared in Limerick, but instead comes from Cork butchers. Packet seems to be known as Drisheen down there. I don't know if Tripe and Drisheen is as popular there as it was once upon a time in Limerick.
Apparently, packet and tripe should only be eaten if the letter "r" appears in the spelling of the month.
It is important when eating packet and tripe to first add a large knob of butter, and plenty of salt and pepper. Then, sit back, enjoy the aroma, and dig in!