Brazen, impudent, or shameless; describes someone who behaves boldly without modesty or restraint.
彼は面接でふてぶてしい態度を取り、評判を落とした。
He took an impudent attitude at the interview and damaged his reputation.
店員に偉そうに命令するふてぶてしい客がいた。
There was a brazen customer ordering the clerk around.
あの子は年の割にふてぶてしいところがあるね。
That kid is rather cheeky for their age.