TO BE AS SNUG AS A BUG IN A RUG

WHEN YOU ARE COZY AND CONFORTABLE, IN A SAFE PLACE OR POSITION YOU CAN SAY THAT: YOU ARE AS SNUG AS A BUG IN A RUG.

WHEN YOU WANT TO DEFINE THE WAY A KID IS SLEEPING, YOU CAN SAY THIS IDIOMS TOO, BECAUSE THE KID'S SMALL BODY IN THE BIG BED IS LIKE THE BUG'S SMALL. BODY IN A BIG RUG.

IN SPAIN WE CAN SAY: "ESTAR TAN AGUSTITO".