: a mass or layer underlying or supporting something laid over it specifically : a mattress laid under a feather bed.

What does hiding underneath the bed mean?

to avoid talking about (sth embarrassing) pardon my French id. the phrase is uttered in an attempt to excuse the user of profanity or curses in the presence of those offended by it under the pretense of the words being part of a foreign language.

What is meant by Reds under the bed?

red under the bed (plural reds under the bed or reds under the beds) (slang) An insidious communist presence; a communist who has infiltrated capitalist society.