Birthday Present for a 5 Year Old Boy?

My little boy is having his birthday party in conjunction with two other family members. We are doing a huge family/friend get together. So today I get a message from a friend of the family who is coming wanting to know what to get him. I can play the "no gift is necessary" card that I really want to play for a number of reasons. First, she and I aren't the best of friends...we tolerate each other b/c of mutual friends. Secondly, I don't want her to FEEL like she has to buy him something. However, I know this person well and that this will not deter her from getting him a present. So my question is, what is an appropriate response to her question. He has no clear "hobbies" or "interest" at this point that differentiate him from other 5 year old boys, so I am stumped...I really don't know what to get him myself as he says when I ask. "I have everything I want."