Not too many tours reach "legendary" status, no matter the band, but the Sex Pistols' original American tour in'78 certainly fits the bill. It went down in rock'n' roll history as a complete and total failure. Malcolm McLaren decided that it would be a good idea to take them on a seven-city southern tour, literally a series of honky tonks and cowboy bars.
As far as McLaren's sworn allegience to total and complete chaos, it was right on brand. It went pretty much as expected: musical incompetence, crowd antagonism, physical altercations--all of it culminating in their famous final debacle at San Francisco's Winterland Ballroom (you can catch the entirety of it on YouTube, I'm sure, if you can make it through). The first big mistake was listening to McLaren in the first place (about anything), and their second biggest mistake was recruiting Sid Vicious on bass (more on him when I list the Sid shirt I just got). Bottom line, if they had retained original bassist Glen Matlock, and if they'd played the cities that they would play two decades later on the Filthy Lucre tour (Boston, New York, Los Angeles), who knows what might've happened. Perhaps we'd have gotten another album out of them, at least.
But that's neither here nor there, and if any merch from the'78 tour currently exists, I don't know about it (hard to imagine, being the monkey-dick operation that it was, that any ever existed). In decent condition, it would be worth a fortune, I'm sure. But at least we have this: tour merch from the Filthy Lucre tour of'96. This one's a good one, too: all cotton, broken in to perfection and flawless. Single stitch (luckily: double stitch was becoming the standard around this time).It's totally comfy and soft as a dream. At 17" pit to pit and 24" back collar down, it's a bit small for a medium tee, but it still fits me perfectly (see pic). So as far as actual Sex Pistols merch goes, this is probably the closest we'll get (some original Vivienne Westwood stuff still exists, but you'll pay out the wazoo for it). So get it while you still can.