flasher

flasher
/ˈflæʃə(r); `flæʃɚ/ n
1 (infml 口) person who flashes (flash2 5) 猥亵性瞬间展露性器官的人.
2 (device that controls esp a) flashing light on a vehicle used to indicate which way the vehicle is turning （尤指）车辆转向闪光指示灯（的装置）.

牛津英汉双解词典