Is it normal to make fun of the client and be sarcastic back when I'm doing it to her? I'm not excusing my behaviour entirely, but I didn't want to be there, and had an exam in 3 hours!!

Part of a therpaist job is to repeat back to the client either by exact wording and behavior what they the therapist is hearing and observing. I forget the professional terminology for doing that but the purpose of it is so that the client feels heard, validated and sees what the therapist is seeing and hearing,

when I was in a parenting class it was with a therapy agency and a therapist ran the class and used her therapy sessions sometimes as examples of how to parent a child. and she used this example of the therapist copying the clients behavior and words as an example of how to talk to a highly upset child by getting down to their level of understanding and height.

When my therapists do this to me I don't pass it off and keep quiet about it. I tell them "ok point taken I was being sarcastic and you didn't deserve that" and then explain why I was being sarcastic and rude. I do that because I know therapist can't help me if I don't be completely honest with them and hide behind sarcasm, and so on. If I don't want to be in that days session I don't take it out on my therapist. I call them and tell them I'm not coming in today because and then tell my reason. or I go to the session and right off say "I don't want to be here today" or "I almost didn't come today because..." or "I only came in today to let you know Im not staying because... and it was too late cancel the appointment." By doing this my therapist knows whats going on with me, I am disrespecting my therapist, an my therapist knows she can use the session time for other things then being subjected to being disrespected and worrying about why I didn't show up to sessions.