Denki Kaminari started a trend around Class 1A. He once winked at Todoroki to see what his reaction would be and Todoroki would try to wink back but since its his first time, he always ends up blinking instead.

From there on, every single time something was happening, no matter what was happening, anytime someone winked at him, he would stop what he's doing and try to wink back, still blinking in the end.

One day, you decided to try this theory out and winked at him.