If you say that someone is stand-offish, you mean that they behave in a formal and rather unfriendly way.

What does acting standoffish mean?

Someone who's standoffish is aloof or unfriendly. When you first meet someone, she might seem standoffish when really she's just shy. A politician who appears standoffish will have more trouble getting elected than one who seems warm and likable.

What does being a LOOF mean?

Smart sailors wanting to avoid a hazard on the leeward side would give the order, "A loof!" From this command we get the idea of steering clear of something (or someone). In modern usage the word has taken on a negative connotation: an aloof person is often considered cold or snobby.