Mindboggling sentence, I've read it several times and still, this must be what it feels like to experience a mild stroke.
“From the tuna picture, I wonder if she is the string-thong [bikini wearing], salt-water-fishing chick, [who is] famous on youtube.”
Either that, or it is a play on that old joke. “I once caught a tuna in my string-thong bikini - how he got there I’ll never know!”