[Serie: All About Japanese Particles]
1. Despite the fact that, though.”
Note: This usage is similar to that of no ni (#30, no. 1), but there is an added feeling of censure or contempt.
子供のくせに、大人の話に口を出してはいけません。
Kodomo no kuse ni, otona no hanashi ni kuchi o dashite wa ikemasen.
Children shouldn’t interrupt when grown-ups are talking. (Lit., Despite the fact [or considering the fact] you are a [mere] child, you are not to butt in on grown-up’s talk [the way you are doing].)
あの人は能力もないくせに、地位だけは欲しがっている。
Ano hito wa nōryoku mo nai kuse ni, chii dake wa hoshigatte iru.
Despite the fact that he has no ability, all he wants is status.
2. Used at the end of a sentence to express censure or contempt.
あなただってできないくせに。。。
Anata datte dekinai kuse ni …
As if you could do it yourself. (Lit., Despite the fact that even you couldn’t do it [you are trying to tell me how to].)
自分でもわからないくせに。。。
Jibun de mo wakaranai kuse ni …
As if you understood. (Lit., Despite the fact that even you don’t understand [you presume to give advice to others].)
– Source: All about particles – A handbook of Japanese function words –