(someone is) buckled up

A "buckle" is the part of a belt where you attach the two ends to each other. The belts people wear on their pants have buckles. So do some shoes, straps for handbags and luggage, and seatbelts.

The buckle on a seatbelt gives us the phrase "buckled up", which means having your seatbelt closed and attached.

All (adjective)?

When you ask "All ___?" it means "Are you completely ___?" For example, if you're getting ready to leave home for a vacation, you can ask your family:

All set?

If it's a cold day and you've put an extra blanket on your daughter's bed, you can ask:

All warm and comfy?

This phrase sounds really positive and comforting.