An emphasized version of the word prawned, used to add more weight to the word, while also implying that they are less masculine than the person who prawntanged them. It also happens to sound like the word poontang, a slang term for the vagina. This makes it popular with 14-year old gamers such as myself, who get a kick out of this sort of thing
"Ha! He prawntanged you!"
"Dude, I got totally prawntanged by a spawn camper on Halo last night."
"Heh. I prawntanged the noob."