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Related to clam: clam up
close as a clam
Safe from harm. Likened to a clam closing its shell to protect itself. All of the doors and windows are locked. Don't worry, we'll be close as a clam in here.
happy as a clam at high tide
Very joyful and content. Clams are dug at low tide, so a clam at high tide would be able to remain uncaught. Look at your sister out there! She's happy as a clam at high tide now that she's back in the starting lineup again. I know I'll be happy as a clam at high tide once I get this stupid cast off my leg.
to say nothing. (Closing one's mouth in the way that a clam closes up.) The minute they got him in for questioning, he clammed up. You'll clam up if you know what's good for you.
*happy as a clam (at high tide)and *happy as a clam (in butter sauce); *happy as a lark; *happy as can be
contented; very happy. (*Also: as ~.) I've been as happy as a clam since I moved to the country. I don't need much. Just somewhere to live, some work to do, and a TV to watch, and I'm happy as a clam at high tide. Matthew was happy as a lark throughout his whole vacation. Bob was happy as can be when he won the lottery.
to refuse to talk or answer Every time I think he's going to tell me what's bothering him, he just clams up.
Etymology: based on the behavior of a clam (a sea creature), which quickly closes its shell when something touches it
(as) happy as a clam
very happy I am happy as a clam living all by myself in this little house by the sea.
Etymology: based on the full form of the phrase happy as a clam in mud at high tide (a clam that cannot be dug up and eaten, which therefore could be considered happy)
be as happy as Larry/a sandboy(British & Australian) also be as happy as a clam (American)
to be very happy and to have no worries We married nine days after we met, and three years on we're happy as Larry. Since he's been at college he's as happy as a clam.
See also: happy
shut up like a clam
to suddenly stop talking and to refuse to say any more
Usage notes: A clam is a fish with a shell which closes up very quickly if something attacks it.When I asked him about his trip to Korea, he shut up like a clam.
Refuse to talk or respond, as in Whenever she asks her teenager about his activities, he clams up. This term alludes to the tightly closed valves of a live clam. [Slang; early 1900s]
happy as the day is long
Also, happy as a lark; happy as a clam (at high tide). Extremely glad, delighted, very cheerful, as in He was happy as the day is long, or When she heard the news she was happy as a lark, or Once I got the test results I was happy as a clam at high tide. The first of these similes dates from the late 1700s. The second alludes to the lark's beautiful, seemingly very happy, song. The third, from the early 1800s, alludes to the fact that clams can only be dug at low tide and therefore are safe at high tide; it is often shortened to happy as a clam.
To refuse to talk or to stop talking suddenly: The politician clammed up when the reporters started to ask about the scandal.
1. n. a dollar. (Underworld.) You got a couple of clams I can bum for a little bottle?
2. n. a tight-lipped person. Suddenly, she became a clam and wouldn’t talk anymore.
in. to get quiet. (see also dummy up.) The minute they got him inside the cop-shop, he clammed up.