Crossing the street (from the middle) without using the crosswalk.
Keep An Eye On Him:
You should carefully watch him.
Keep body and soul together:
To earn a sufficient amount of money in order to keep yourself alive .
Keep your chin up:
To remain joyful in a tough situation.
Kick The Bucket:
Diagonally across. Sometimes called Catty-Corner as well.
Knee Jerk Reaction:
A quick and automatic response.
Knock On Wood:
Knuckle tapping on wood in order to avoid some bad luck.
Know the Ropes:
To understand the details.