Learn English – the scientific term for a habit of doing something without realizing it until someone points it out to you

I've heard the term verbal tic used in this context, for habitual expressions that the speaker jams into sentences irrespective of meaning or sense; I overheard one a man say:-

"To be honest with you, Spurs won 2-0. You know what I mean?"

As no-one could doubt his honesty in reporting a football score, or entertain any doubts as to the meaning, I'd guess this is the sort of phrase you are interested in. He'd add one (or both) of those little fragments to practically everything he said.

This sound is used as an actual phoneme in many African languages such as Xhosa. In other words, in many languages this sound appears as part of a word. The technical name for a sound of this type is an unvoiced alveolar lateral click. In English speaking cultures, this sound is only used non-verbally, where it can have a variety of meanings. For example, English speaking horse-riders will use this sound to encourage their horses to start to move, or speed up. We also sometimes use this when winking as a gesture of camaraderie with the person we're winking to.

For an audio example of a voiceless alveolar lateral click see here.

For instructions on how to make them, see this video here.

If unvoiced alveolar lateral click is too long, you could of course, refer to it simply as a click.