Anti-premium LLLL.coms was a joke someone started because there was so much talk about premium letters. An anti-premium is a LLLL (four letter domain) with three or four JKUVWY and particularly QXZ. (Purists would insist on one each QXZ and one JKUVWY, no duplicate letters, either.) In otherwords, by conventional wisdom, one of the worst possible LLLL's. The term has caught on and I expect in twenty years at the bi-annual Southbys domain auction the auctioneer will praise the qualities of the fine anti-premium LLLL.com up for bids.
<----- way off topic.