I make them for my granddaughter using the cartoon characters that she loves so much.
When she moved to her "big girl bed" she only wanted to lay down in it for the first time because she had her "Tinkerbell pee-wo". My son said that it was "genius" of me to make it! Ha ha ha ha ha.
Now she has Dora, Cinderella, Buzz Lightyear, Woody & Jesse, and an extra Tinkerbell (so my DIL doesn't have to do an extra wash everytime my DGD wants it.)
Fun to make too!