These three belong to three different clubs.
First one, very popular, is singles only club. It is closed for new membership.
Second one, very useful, is for singles and couples. It is open for new members but very hard to get in now.
Unlike the first two, the third Club is different for these three. The three singles are inter-related to each other. Especially two of them are constantly talked about daily.
Outside these clubs, when the three come together, you are looking at very popular food!
Who are they? What are the three clubs?
They are not words