maths is quite a strong point and i often use + or - 100% when comparing relative rates between currencies, or realised profits on a short or long
Yes technically you cant lose more than 100% of something however your perceived losses can be described as 150 %, whether is right or wrong is useful way or seeing things.
as an example, if i brought a car for 1000 dollars it broke down immediately and i had to get it towed and dumped costing another 500 dollars. In my mind i lost 150% on that investment. I know i haven't lost more than 100% of my car lol