Need help about sumthin lol?

k so yesterday i asked a question on how to get out of gym cl.....and i got a couple of answers so i thought of punching my face real hard and pretending that i twisted my foot.....and told the gym teacher that i fell down the stairs and could not participate today....obviously something like that doesn't cure in a day....the teacher said that i needed a note from my parents so i could be sitting out tomorrow.....can anyone or any parents out there tell me how you would write a note saying that i tripped over my shoelace at home and fell down the stairs and hit my face and smashed my foot?....please help....do not want to get in trouble for lying tomorrow :P