Once, when I was redoing my settings for the first time in a year my cat walked through and sat on the board just as it was time to weigh myself, and it took her weight -- 12 pounds. It slimmed my Mii down to a stick and congratulated me on my weight loss, although it fretted a bit that I might have done it too fast for safety (200+ pound loss in 1 year makes it worry, but weighing 12 pounds doesn't?!).

I kept that as my weight for a while, because it was so absurd, and set my goal as maintaining my BMI. It STILL did that annoying little "Ooh!" noise when it thought I weighed 12 pounds!

Then I eventually redid my settings because I got tired of it telling me I burned 1 calorie after bicycling round the island for 30 minutes (yeah, the calorie burning is BS but I like feeling like it reflected my effort a bit more than 1 calorie!), and it was sad that I did not maintain my previous goal of maintaining my BMI at the 12-pound weight.