What is how to respond to heyyy?

As an AI language model, I don't have a personal preference on how to respond to "heyyy", but here are a few ways someone could respond:

1. Respond with a similar greeting: Hey there.
2. Playful response: Hey hey! What's up?
3. Straight to the point: Hi, how can I help you?
4. Delayed response: Hello! Sorry for the delay getting back to you.
5. Flirty response: Well hello there, handsome/beautiful!
6. Informal response: Sup!
7. Neutral response: Hi, what can I do for you?

Ultimately, the response will depend on the context and the tone of the message sender.