Happy birthday, but not TOO happy
"or just have a candle sitting down, sing happy birthday, blow out the candle and eat the food!"
Candles are dangerous. You could spill hot wax on a child and set she/he/it on fire.
EPA recommends using an environmentally-safe mercury-filled lightbulb in an approved lamp, if you must extinguish some kind of light. Better for the environment if you just thought about a light going out. And don't sing. It creates CO2.