The Cupcake Knife is a Knife Texture in the colors of a cupcake, with pink and purple colors all over and white at the end, representing icing. The Cupcake Knife costs 7 credits per round as murderer and it costs 100 credits to buy permanently. Later, in the XMAS update, you can only buy knives and accessories permanently.
The question is, does it have frosting? Yes. Yes it does.