buy your child a scarf or pillow case for their birthday. Tell your child you are not wrapping their present, you are hiding it in their room to find, but to make it a challenge you have to be blindfolded. Blindfold them with a sleepmask and then the scarf. Take them to their room and watch them, feel around for a unfamiliar object. See how long it takes them to figure out their blindfold is their present. See if they know the contents of their room.
On the theme of opening presents blindfolded, wrap up a scarf and as soon as they unwrap it, say “here, let mummy help you try it on”, and blindfold them without warning. Don’t try this unless you know they don’t mind blindfolds.