Can you target a stunned unit with Facebreaker to trigger stun-related effects like Leona?

Ruling: You can target stunned units with Facebreaker, but stunning an already stunned unit does not trigger effects that require a unit to become stunned (like Leona's ability).

Nuances:

• You can use Facebreaker multiple times on the same unit to stun multiple different attackers
• Applying stun to an already stunned unit does not count as "becoming stunned" for trigger purposes