to sulk; to get in a huff (to become sulky or cross, often stubbornly so)
子供が自分の思い通りにならず、へそを曲げている。
The child is sulking because things didn't go their way.
彼女は冗談を本気にしてへそを曲げた。
She took the joke seriously and got cross.
すぐにへそを曲げるタイプだから、扱いが難しい。
She's the type to sulk easily, so she's hard to handle.