To take a "selfie" after you've hit the gym and you're swollen. Normally posted to Instagram or Twitter or sent in a Snapchat, to make yourself appear to be bigger than you actually are. Mainly taken by "bros", and insecurepeople who need others to reassure them that they are the most muscular douchebag around.
I looked like a total douche taking a swellfie in the locker room but the girls on Instagram will love it.
A photograph of oneself or a group including oneself that features any type of shell, including seashells and turtle shellsA photograph of oneself or a group including oneself that features any type of shell, including seashells and turtle shells
"Hey Jim, thats a cool shell over there, lets take a shellfie with it."
"Good ideaBob."