Riddle

Here's a tricky one I crafted with a friend: Squirrel Girl and MCU Captain Marvel each take a full week to be permanently erased (from head to toe) by Stan Lee. He chose a pink 'For Big Mistakes' eraser to do it with optimal speed. They are erased at inconstant rates - there are spots where they are erased a little faster and spots where they are erased a little slower, but they still both take a full week to be erased by Stan Lee.

You have to measure precisely 5.25 days, no counting allowed. There is no way to tell how much time is passing other than that. How do you and Stan do it?

Edit: To help you and Stan out, Stan was gifted the power of Shape Shifting. And a back-up bag of 'Big Mistake' erasers were given to you guys as well.
Please note: This is purely for comedic purposes.

A prisoner is told "If you tell a lie we will hang you; if you tell the truth we will shoot you." What can he say to save himself?