The uncontrollable urge to reproduce that consumes a female while she is holding a baby. This gut instinct/desire is completely independent of her true thoughts on having (and raising!) children.
Meredith never wanted kids, but every time she held her niece, her mind went blank and her ovaries starting churning--all was complete and perfect in the world. Truly nutty biology was at work- she was having a womb boner.
A person who is easily distracted. Someone whose focus is often directed away from the present situation.
Teacher 1: How many butterfly chaser's do you have this year?
Teacher 2: Just one; but he's really bad. This morning during grammar I thought he was going to run out of the room to chase a butterfly he saw from the window.