Never ever order the Subway tuna. Multiple studies have come out that not only is it usually not tuna, its usually not even fish. Subway tuna is mostly just chicken and mayo.
Mashing together those two lessons, I'm reminded of my early high school days. Coming back home from a school trip, the classmate I was sitting next to on the bus ordered a seafood and crab sandwich when we stopped at Subway. I (with my plain old Subway Club) was making fun of her for her choice... so she proposed a trade. Half my club for half her seafood sub. Thus called out, I had to agree. Two things happened from that day forward. First, I never ordered anything other than the seafood and crab at Subway ever again. When they stopped selling it, I stopped going there entirely. And Second, my friends to this day still refer to it as the day Emily gave me crabs.As a kid, I never liked condiments like ketchup, mustard, and mayonnaise, and pretty much associated other condiments like relish and sauerkraut with them assuming I didn't like them by association. Fast forward about 35 years since I took my stance on condiments, my gf convinced me to try sauerkraut when she basically said "it's just cabbage and vinegar, and you like both of those things." I honestly never knew what sauerkraut was; I just disliked it because it sat on the table next to the unholy trinity at many a cookout. And now I love sauerkraut.
Long story short: don't be afraid to try "new" things. (Except ketchup, mustard, and mayonnaise; avoid those at all cost.)