He likes to rank his friends by tiers, which makes people uncomfortable.
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From Cao Xueqin's Qing novel 《红楼梦》 (chapter 75): a character scolds the young masters, 只不过这会子输了几两银子,你们就这样三六九等儿的了 - just because they lost a few taels of silver at gambling, they now divide everyone into grades. The numbers 3-6-9 evoke "many uneven ranks."
usage
Almost always with 分 (divide) in front: 分三六九等. Often carries a critical tone - the speaker disapproves of such ranking. Related nouns: 等级,阶层.