I was taught as a child to open plain envelopes first. Checks, credit cards, and other important stuff are put in boring envelopes.
I worked for a CC company and when we mailed checks to customers we told them "This check will come in a plain white envelope." And the amount of people who thank me for letting them know because they might have thrown it away.
Over my life I've had several shoes and other clothes that I wish when they wore out I could have bought more. Thankfully my favorite shirt right now I can. It is a tshirt from Hot Topic. It says it is the Dark Phoenix but I know it is Kitty Pryde using shi'ar tech to look like the Dark Phoenix and it amuses me to wear it. I have several times worn it and said "Do you like my Kitty Pryde T-shirt?" And people being confused. The shirt is also very comfortable.