Yoruichi is your sensei (teacher).. she called you to come the forest to train there under her watches! You went there and trained hard.. but actually she was naked and standed Infront of you. You said: Hey sensei.. what kind of this train.. while you are naked Infront of me.. how I can focus on my training? (She doesn't care what you say just smiles. She just wants to say: Go ahead and keep training!)