1
general::
Very cozy and comfortable, as in During the blizzard we had plenty of firewood and stayed in the cottage, snug as a bug in a rug. This expression, thought to allude to a moth larva happily feeding inside a rolled-up carpet, was first recorded in 1769 and probably owes its long life to the rhyme.
American Heritage Idioms
2
general::
Phrase(s): *snug as a bug in a rug
Cliché wrapped up tight, warm, and comfortable. (Playful; often used when addressing a child. *Also: as ~.) • The bedroom in Aunt Jane’s house was cold, but after she wrapped me up in four or five quilts and put a stocking cap on my head, I was snug as a bug in a rug and ready to go to sleep. • Alan: Are you warm enough? Jane: Yes, I’m as snug as a bug in a rug.
McGrawhill's American Idioms And Phrasal Verbs