Humming during blowjob

I heard about this technique where you hum to ease your gag reflex allowing you to deepthroat. I would love to try this but how are you supposed to hum? I keep picturing myself going down on him just straight up “mmmmmmmmm 😐” but obviously that’s not very sexy. What do you guys do? Do you just make sounds as if your enjoying it? How do I make it hot?