That’s a foul in cricket.
The general point is that the batsman can’t use his body to keep the ball from hitting the wicket – he has to use the bat. But it’s apparently a confusing rule, and/or difficult to apply correctly.
And it’s a wonderful way to describe a messed-up situation without swearing. Use in place of FUBAR (you know what that means, right?)
“These days the entire US political system is leg-before-wicket.”