A costume for your baby is probably the last thing on your mind. You're more preoccupied with learning to sleep while standing or finding out just how much fluid volume a baby can hold. So I'll keep this short and show you what you should not put your baby or toddler into.
The idea of a boxer costume is not bad at all. However, you have to realize that putting boxing gloves on a small child will result in more than one person getting punched in the genitalia.
You're thinking, "Oh, we could get more than one use out of it if we take him to Star Trek conventions." Please stop thinking that or else your child will grow up to be exaclty like those jocks that bullied you in high school.
Now the two most poorly concieved costumes:
I am speechless.
If you put a child in this costume, you should have your kid taken away. Why? Because if you put a baby in a whoopie cushion and take him/her to a party, someone will think it's funny to sit on your baby. It won't be funny for long.