“It's way past your bedtime!”
You went out with your wife and left your son with a family member for the evening. He's supposed to go to sleep at 9:00pm, but when you get home at 10:00pm, he's still awake.
It's way past your bedtime!
"Way" means "far". You can use it like this:
I was out way past midnight.
This means that you stayed out not just until 12:05 or 12:30, but several hours past midnight.
Here's another example:
There's no use apologizing now. We're way past that point.
You might say this if someone has made you so angry that there's no chance that you'll forgive them.
Parents often set a specific time for their children to go to sleep each night. We call this the "bedtime":
You know that your bedtime is at 9 o'clock. What are you still doing up?
We sometimes use the word "bedtime" jokingly to talk about adults as well.
I gotta go home it's way past my bedtime!