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1.
a tiny little fucker that packs a massive punch. jelly nets do nothing to stop them. box jellies are just as bad. often known as the asshole of the sea.
i got stung on the ass by an irukandji while surfing up in cairns, and ended up in the hospital for 3 days. i hope these fuckers go extinct.
by AuSSiE BuGGaZZ February 01, 2010
 
2.
Noun. A name used to describe a species of VERY DANGEROUS jelly-fish about the size of a finger nail. It's venom is said to be a hundred times that of a cobra and it can kill a human in two minutes if the wound is not treated. If the wound is treated...be prepared for some MASSIVE pain.
Oh my god,IRUKANDJI!
by DarkPhantum June 04, 2006