The Knee Catch
To make a knee catch throw a club across slightly lower than normal, but with the usual amount of spin. Twist your body slightly towards the club and catch it by bending your leg at the knee:
Pointing the handle of the club in a bit as you make the throw may make the catch easier. To carry on juggling after making the catch either drop the club down to a kick-up, or strike the knob with another club so that it shoots straight upwards.