informal

to be able to understand something.

He's tried to explain the rules of the game dozens of times but I just can't get my head around them. (usually negative)

• be quaking in boots
• be quaking in your boots
• be quickest off the mark
• be quick off the mark
• be quick on the draw
• be quick on the uptake
• be quids in
• be raring to go
• be ready to roll
• be riding for a fall
• be riding high
• be right in the head
• be right on the money
• be right up alley
• be right up arse
• be right up someone's alley
• be right up someone's arse
• be right up someone's street
• be right up street
• be right up there with
• be right up there with someone
• be right up there with something
• be rolling in it
• be rolling in the aisles
• be rotten to the core