To sign ketchup, take your non-dominant hand and form a fist. This will represent the bottom of a ketchup bottle that you're holding upside down. Then take your flat, open dominant hand and make a pushing motion above the "bottle" hand, as if you are trying to push ketchup out of a full, freshly opened bottle.
You can use ketchup to expand your baby's vocabulary of favorite foods and condiments.
Use the ketchup flash card in conjunction with popular food items such as chicken nuggets and french fries.