a soft giggle
A soft giggle is when you laugh but it’s like you’re trying not to let anyone know you’re laughing. It’s like a tiny chuckle that won’t shut up.
My friend saw me eating a taco and did a soft giggle. I knew I was busted.
She heard my joke and did a soft giggle. I knew it was fake.
He did a soft giggle when I tripped. I wanted to punch him.