Informal: easy; something that can be done with little effort.
その数学の問題はちょろいよ。公式さえ覚えればすぐ解ける。
That math problem is easy. Once you remember the formula you can solve it quickly.
このバイトは覚えればちょろいから、初心者でも大丈夫だ。
This part-time job is easy once you learn it, so even beginners are fine.
彼には内緒でやったけど、ちょろい相手だったからバレなかった。
I did it without telling him, but he was an easy target so he didn't notice.
Informal: simple-minded or easily fooled; obvious (as in a trick that someone easily falls for).
あの客はちょろいから、セールストークで何でも買ってしまう。
That customer is gullible, so they'll buy anything with a sales pitch.
そんな噓はちょろいよ。すぐ見抜かれるって。
That lie is too obvious. They'll see through it immediately.
彼女はちょろい性格で、みんなに甘えてしまう。
She has a naive/simplehearted personality and ends up depending on everyone.
Informal: lax, slack, or weak in attitude or response; not firm or strict (often with disapproving nuance).
上司の注意がちょろいから、部下はルールを守らない。
Because the boss's reprimands are lax, the subordinates don't follow the rules.
彼の説得力はちょろいので、みんな本気にしなかった。
His persuasiveness was weak, so nobody took him seriously.