These are the Nyanko Charge Cat Head Phone Chargers available for sale from the Japan Trend Shop ($72, cheaper elsewhere if you're cool ordering directly from a Japanese website). Available in Persian, Garfield, Blue Eyes, Green Eyes, and Orange Eyes varieties, each 4400 mAh battery pack takes about five hours to charge, and is expected to last at least 500 charges. I remember I bought one of these USB phone charging battery packs from the dollar store once, then one night at the bar and it felt like my penis was roasting like a hot dog and I yank the battery pack out of my pocket and it is hot. Like HOT hot. So I casually but quickly stepped outside into the alley behind the bar and 100% TRUE FACT: that's where the term dumpster fire originated.
Keep going for a couple more shots.
Thanks to Allyson S, who agrees the best portable phone charger of all time is a modified golf cart battery.