Take note, cats in the window, THIS is how us dogs take charge.
Just grab the Flexi while mama isn't looking and RUN.
It will still be attached to you, of course, we wouldn't want to do anything stupid...
Does your mama try to take back the Flexi? There is no reason to stand for that (well, you may have to stand up as I do to grab it).
Your mighty jaws should take care of getting that Flexi back into it's rightful hands (uh, jaws).
Slobber is your friend in this battle. It will make the Flexi more slippery to those non-fuzzy paws the humans have, and apparently they don't like to grab a handful of it. Use this knowledge wisely.
And as always, busting out a huge smile can get you pretty much anything you want. See?
Thank you, mama.
Oh, I shall humor you for a little while, allow you to hold the dog-spit-covered Flexi. At least while we're in the park, then it's mine again ok?