Waterproof After 18
How is it that a person can look you directly in the eyes and call themselves an adult if they use an umbrella? If it’s raining, there’s no need for umbrellas or raincoats or anything else! You live with the rain! That’s how adults in society function! Either get with the program or go back to elementary school!
Obviously, we’re kidding. As one commenter pointed out, you don’t turn waterproof just because you hit the age of 18. You don’t instantly receive an IP67 rating when you graduate high school. The only argument you can use against umbrellas is that it turns you into a lightning rod.