I had this problem the other day and was very proud I figured out how to fix it. I just wrote this for fun.
How to remove a toothpaste cap from a sink’s drain.
What You Need:
- A stick-like object, approximately 4 inches long
- Pliers
- Dish Soap
- At Least Two Hands
Step One: Insert the stick-like object into the drain.
Step Two: Wiggle it around until the cap sits “cup-side” up.
Step Three: Position the stick-like object inside the cap.
Step Three: Slide the cap and stick-like object up the side of the drain.
Step Four: As you reach the top of the drain, grab the pliers.
Step Five: Use the pliers to grasp the cap.
Step Six: Remove cap from drain.
Step Seven: Throw cap out, because now it’s very gross and you wouldn’t even think of putting it back on the toothpaste.
Step Eight: Use dish soap to wash stick-like object, pliers, and hands.
Congratulations! You’re drain is now free and clear. You can resume using it as usual. 
