WPS - Writing Prompt Postcard #8

I've had lots of requests for postcards swaps with writing prompts for what to say on the back, so that is the inspiration for this swap series. Each prompt will be different, so be sure to keep reading to find out what this one is. You will have 2 partners and you will send each partner a sender's choice store-bought postcard. No handmade postcards or free ad cards. Vintage, Zazzle, artsy, touristy, etc. are all fine. Follow the writing prompt for what to say on the back of the postcard, stamp it and send it on!

The prompt for this postcard swap is:

Username!

Tell your partner how you came up with your username or what it means. Some seem obvious but some have me scratching my head!