The worst was when we had to keiko together. We were about the same rank (yon-kyu) at the time, so we had a lot of jigeiko with each other. Frankly, it's really awkward: you look at this girl you're with, and can't bring yourself to attack or do anything. It really comes down to a tsuba-zeriai nothing-fest where both of you just kind of rest until you start fighting others.