know one's onions

But take it from me, he knows his onions,' Hoppie confided.

"As you'd expect, he really does know his onions in this form of the game."

Whoever picked him for the job knew his onions.

The pilots and airborne reporters really know their onions.

This guy really knew his onions, I'm not kidding.

Although you have to admit the professors knew their onions.

"And now we're going to have some fun, if I know my onions," the man in black smirked.

But when it comes to the realities of politics, the greens know their onions.

The old boys will be back - and they all know their onions.

The person who said, "Love at times may be fleeting," certainly knew his onions.