foul up

foul up  {v.},  {informal}

1. To make dirty.

The birds fouled up his newly washed car.

2. To tangle up.

He tried to throw a lasso but he got the rope all fouled up.

3. To ruin or spoil by stupid mistakes; botch.

He fouled the whole play up by forgetting his part.

4. To make a mistake; to blunder.

Blue suit and brown socks! He had fouled up again.

5. To go wrong.