"Guess the gender" ideas for baby shower?

I'm planning my SIL's shower and they do not know the gender. I wanted to ask the guests to guess the gender (weight, date of birth, name etc). Any ideas how? I was thinking of cutting blue and pink paper into onesie shapes and having them write on those then throw into a fishbowl...but I'd also like something she may want to save (and who wants to save 60 lil pieces of paper?). Like a scrapbook??

Any ideas? TIA!

Re: "Guess the gender" ideas for baby shower?

i went to a shower and this was the theme,had to pick a team

when u walked in u had to pick a button,blue or pink they had the stick figures like on a bathroom door lol

they had a board and everyone voted on sex weight wtc

the favors were blue and pink soda witha matching straw and what u thought she was having u took

also on the cards where u guessed whoever was closet when she had the baby the mom sent a prize