"Tsh" sound like someone would say, I'm not sure what to call it, a snort maybe? Vegeta in Dragon Ball often makes this sound.
2 Answers
チェッ、ちぇ、ちっ、チッ、ちぇっ. A form of 舌打ち{したうち｝ As in 「チッ、くだらん、なにがホグワーツ魔法学校だ！」 Weblio definition link here.
Isn't it ちゅ? Sometimes like for ます、です う is not pronounced. I hope I helped you :)
Maybe this onomatopoeias : ちゅっ
