I was asked this question and thought it was an interesting one.
On the initial deal, the dealer deals a card between seats 2 and 3. Before the dealer has had a chance to tell seat 2 to take his card, seat 3 (thinking it is her card), takes it and looks at it instead of her proper card. The deal has not yet been completed, and not all players have even received their first card.
a) Do you continue to deal, or call a misdeal?
b) If you continue to deal, does seat 3 keep that card?
c) If seat 2 (or seat 3) needs a replacement card, where will it come from?