We've all done. Myself more than I care to mention!
One good one was whilst sitting ready to go at Stansted one day, when someone decided it was a good idea to do their entire PA announcement on the ground frequency. A fairly rountine occurance, but in this case the chap making the boo-boo decided to apologise for the delay they had by blaming ATC........
Quick as a flash the ground controller came back with "you weren't delayed by ATC before, but you are now!"
All jokingly of course.
The chaps at Sarfend are very good and are nice blokes with it. They are well used to students and everyone else making a horlicks of it.
Don't worry about it, you'll do it again, it's just as you get more experienced you care less about making mistakes like this.