It is illegal to flirt using your hands or eyes.

The Law

In an effort to maintain public decency during the early 1900s, local lawmakers sought to curb public prostitution and lewd behavior. They passed a broad ordinance banning suggestive winking or provocative hand gestures on public sidewalks. Today, you will not get arrested for a cheeky wink, but the archaic modesty law was never explicitly struck down.