What are some examples of random variables X, A, B such that X is independent to A, and to B, but not to A and B jointly, i.e., X is not independent to (A,B). In other words, $X \perp A$ and $X \perp B$ but not $X \perp A, B$

I got curious while reading http://en.wikipedia.org/wiki/Conditional_independence

It is enough to find examples such that $X \perp A$ and $X \perp B$ but not $X \perp A \mid B$.