What it means
When someone gets stitched up, they've been stitched into a mess not of their making. It could be a friend who drops you in it with the boss, or a deal that's more knotted than a kitten's knitting. It's the art of leaving someone holding the bag while you skip off whistling.
Usage examples
"He totally stitched me up with that fake alibi and now I've got the cops at my door."
"Don't let them stitch you up with the bar bill again, you're too soft for your own good."
"She thought she was getting a bargain but it was a right stitch up—the car's a wreck."