V_T, place your arm on a flat surface, hand down, palm down. Fold your middle finger such that the middle segment is flat on the surface, along with your palm, and the palm side of the rest of your fingers. Put a little pressure on your middle finger. Not a lot, but you should be able to feel it. Now, without moving the rest of your hand, raise your ring finger.
Which two fingers are a deformed pair of conjoined twins?