What do i do? i want to but i dont know how..?

okay, i was at my friends house and i saw and heard my best friend masterbating.. she thought i was asleep, but she woke me up with her moaning.. (we are both girls btw. ) i wanted to roll over and say can i help,or something.. i really wanted to, but i totally trust her and stuff.. i just dont know what to say... help me?(: