They actually go by themselves when you put Mingle on the miis.
You have to be online for sure...
And there is an option called travel that has bo be on too,
nice avatar by the way, is that your tummy?
Another one had a nice tongue on it's avatar too,
Maybe I should put a close-up pic of my nose... though it won't be that interesting, hehehehehe
(hope all this doesn't come out wrong, I might get slapped or somethin'... I asure there is no bad intentions here.
)