Excel Pikachu

made it in DV-lesson in school ... something went badly wrong. The story:

The teacher told us stuff about excel but i was in excel class for years so i knew all of what the teacher was telling. While the teacher explained stuff i opened the tasks file, solved the task, made a new table (in the same file) and 'drew' this pikachu.
Well ... nothing wrong till this point but then a bad mistake happened: The main file i was working with wasnt protected, i didnt thought about that and saved it. Class endet and the next class entered the room, this class should work with that tasks file ....... the whole class opened the file and saw my pikachu, nobody knew how to switch between the tables.
When school was over some of the studens came to me and asked if i was the one who drew the pikachu, i was shoked and said yes. they laughed and told me that the teacher got really mad and said that he knows who made this....

whooooooooops .........