Yes the 6+ will fit in side of slacks, cargo shorts, and jean front pockets.
My wife and I went to Best Buy to size up similarly sized phones and there was no issue putting them in any of our pockets.
People do realize that many phones are already this big or bigger and already fit in people's pockets right?
Now, if you are into skinny jeans you may be in trouble. I can't vouch for that though since; luckily, I don't have to worry about that.
You'll just look like an utter plonker taking a call on it!
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For those arguing about the plane. China Southern operates varous B-777 cargo aircraft and some airbus A300 cargo variants.
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Note the lack on windows on the one though.