As mentioned in lolxorz, the suffix xorz is substantially more leet than the plainer zorz. So when expressing admiration or amazement, trump the simple leetzorz with the leeter leetxorz.
Its the leetest possible version of the humble Roar!. Spelling is obvious, but pronunciation is odd. Pronounce the roar in the loudest and most drawn out way possible, before quietly adding -xorz on the end.