I guess it depends on who is the recipient of the wink is:

Source: wikipedia

The West
In Western culture, it may be used to communicate sexual intentions, ranging from flirtation to an explicit invitation.

Latin America

In Latin American cultures, winking may also be a romantic or sexual invitation, but may also be used a casual sign of recognition or of acceptance of behavior among friends.

Asia

In many Asian countries, winking may be seen as an offensive gesture. In India, it may be viewed as an insult or an obscene sexual proposition

Africa

Nigerian adults may wink to signal children to leave the room

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