While the definitions describe feelings of anxiety, stomach pain, and queasiness, “collywobbles” is almost exclusively used in a humorous, slangy way. It’s another way to describe “butterflies in your stomach.” There’s also a scientific explanation for this feeling: When you’re in moments of stress, your sympathetic nervous system kicks in (basically what controls the “fight or flight” response). Your body releases adrenaline and cortisol, which increases your heart rate and moves blood flow to your heart and leg muscles — away from your digestive system. This constricts the blood vessels around your digestive system, giving you the feeling of collywobbles.