I've seen:
A sweatshirt with 100 buttons on it, arranged to make a "100".
A big shirt with 100 bows glued onto it.
A sweatshirt with 100 large pom-poms glued on.
A sweatshirt with 100 small iron-on photos showing events in the kid's life. (Fun, but not cheap or fast!)
A shirt with 100 safety pins on the arms. (Although, in this day and age, that might be considered to be a weapon!)
A sweatshirt with 100 buttons on it, arranged to make a "100".
A big shirt with 100 bows glued onto it.
A sweatshirt with 100 large pom-poms glued on.
A sweatshirt with 100 small iron-on photos showing events in the kid's life. (Fun, but not cheap or fast!)
A shirt with 100 safety pins on the arms. (Although, in this day and age, that might be considered to be a weapon!)