Biro is a brand of pens that was developed by the Hungarian inventor Laszio Biro. He wanted to develop a pen that would write under different altitudes without running or splattering. He sent 30,000 pens with British air force pilots during World War II to test his pen. Today, you can purchase a Biro pen. The ink is similar to ballpoint pen ink, but it is thinner. This does not affect your ability to remove it from plastic.
Blot the ink stain with a clean cloth if it is still wet. Don't rub the stain as this will only spread it.
Soak a clean cloth in rubbing alcohol.
Blot the rubbing alcohol over the Biro ink stain. Work from the edges of the stain toward the centre to prevent it from spreading. Use as much rubbing alcohol as necessary to remove the stain.
Add just enough water to 2 tbsp baking soda to make a thick paste if the stain is still visible. Rub the paste into the ink stain until it is gone or until you can't remove any more of it.
Dab acetone onto the ink stain if you can see it. Acetone will remove any finishes or paint on the plastic, so only use it on bare plastic. Work until the stain is gone.
Rinse the plastic with water and dry it.