Crashing in here - need baby shower help

is it inappropriate to have shower guests participate in a baby pool? The would have to pick a date on a calendar and indicate sex, weight, height etc.

If Yes,

how much $$ collected goes to the parents when the baby is born??? Would it be 60% for the new parents and 40% for the winner?

Please help, I am just helping out with the games for a very good friends baby shower...