Did you know you can insert a picture into a comment?
Right click on a cell and select Insert Comment. Remove the username from the comment.
Click the border of the comment to select it. Right click and select Format Comment.
Click the Colors and Lines tab. Select the dropdown arrow under Fill beside Color: Select Fill Effects.
Select Picture…click the Select Picture button….Scroll to find the picture that you want to insert…click Insert.
Click on the LOCK Picture aspect ratio button.
Click OK. Click OK.
How cool is that!