Examples:

• You people in the front row heads up!
• Look, I just came here to apologize to you. Ow! Heads up!
• You people in the front row heads up!
• Well, thanks for the heads up!
• Heads up! I'm coming into the room!
• OK, the payment form has been corrected, thanks for the heads up!
• Well, just set it down on the counter. Heads up!
• Thanks to Daniel L. for the heads up!
• Will dig into this en language hint–thank you for the heads up!
• Whoa! Heads up! Movement on your— Watch out—9:00!