L-plates are square signs with a red "L" at the center. They are placed on cars in Britain to show that the person driving is inexperienced (the "L" is short for "learner"). People also jokingly attach these signs to their clothing before they get married, to show that they are beginners in marriage
Yesterday I got my driver's license but I'm not a good driver. Can't you see my L-plate on my car?
Just the fact that I don't blame myself I'll wear a L-plate on my suit so the people know that I'm inexperienced.