Inspired by the Worst Double Feature thread.
I never saw Jimi Hendrix open for the Monkees, but if you did, you probably win this thread.
Around 1971 or so I saw the Grateful Dead. The opener was a monkey act, i.e., a guy with a trained monkey. He had the monkey smoking cigarettes, among other “tricks.”
For me, it was a triple bill, but the two bands that didn’t make sense for me going together were The Screaming Trees opening with the Spin Doctors headlining. (Soul Asylum was sandwiched in the middle there.) I know, very weak sauce compared to your examples, but to this day I don’t understand how those got on the same tour.
When I saw David Bowie, his opening act was Macy Gray.
Judas Priest had a hair metal parody band called Steel Panther as the opener when I saw them in 2014.
I twice saw the Stones in 1995, and the second time was at the Schüttorf Festival, Germany. There were several bands, but the last act before the Stones was Rüdiger Hoffmann, a German stand-up comedian who had massive success at the time. Problem was, he was known and notorious for his slow pace, in his Westphalian style, that is his trademark. Now the concert was in Westphalia and I’m a Westphalian too, but can you imagine a lamer act to open for the fucking Stones? Me and my girlfriend didn’t even listen. Later, when the Stones hit the stage, Mick welcomed us with “Welcome to the middle of nowhere”.
I saw Buffy Sainte-Marie open for Barenaked Ladies in 2017. The only thing they really have in common is that they’re Canadian (except for Buffy Sainte-Marie).
Not me, but before I knew her my wife went to see Peter Murphy, front man for Bauhaus, and the opening act was Jewel, whose act at the time included a lot of yodeling. I don’t think anybody had ever heard of Jewel yet, and she and her friends were like WT ever-loving F?
I saw the Stones in ‘81, and the first opening act was Ziggy Pop. That might not seem so strange, but it turned out that the Venn diagram of Ziggy Pop and Stones fans was very small. I was still in high school, and I remember going to a jock party a couple weeks before the show where they were bitterly complaining about the fact that Ziggy was opening for the Stones. And when Ziggy played, the fans loudly booed and threw tons of garbage onstage while he was playing. After about 20 minutes he stopped, said “thanks for being such a great audience” sarcastically and left. I remember a janitor afterward using a very wide push broom to sweep all the garbage off the stage before Santana set up.
My contribution: in the very early 1990’s I got to see Low and Soul Coughing play together at First Avenue. Not completely bizarre, but I think the Soul Coughing fans were wondering what Mimi and Al were doing in front of an audience.
A guy named Johnny Cougar opened for the Kinks in September 1980 at the Coliseum on Long Island. Loudly and lustily booed off the stage. Only time I’ve seen anyone booed off the stage at the Coli or MSG. So if opening acts who made it count, that’s all I got.
A few years later he was John Cougar Mellencamp and had a big album, and I remembered him as the guy booed before the Kinks.
Style/genre-wise, I’d say seeing Larks’ Toungues-era King Crimson share the bill with Steve Miller at Winterland and six months later at the Cow Palace with Ten Years After.
You mean Iggy 
? I saw him last year, and he was still great. We were too late to see the opening band, though.
Oh wow. Where did I get Ziggy from? 
I saw that tour. My crowd didn’t boo him off the stage, but we showed him no love whatsoever. I remember he was running around on stage, jumping and waving his arms and doing whatever he could think of to get a reaction. Nothing. He ad libbed a line: “I need a lover who’ll … sit on my face.” (Probably not ad libbed spontaneiously right there on the spot, but I’m pretty sure it’s not on the record.) Okay, you’d think a rock and roll audience would appreciate that, but in this case, you’d be wrong. No interest.
Then the Kinks came on, and Ray had us eating out of his hand from the get-go. It was like someone had flipped a switch.
A decade later, my brother and I saw the supergroup Asia, and the most memorable part of that show (besides Carl Palmer taking his shirt off during the drum solo, which us women liked), was the opening act. The band that was supposed to open had a gig booked in a nearby town, so the replacement was a magician, as in the type one would hire for a kids’ birthday party. We were all booing, except when his scantily clad female assistant walked onstage and all the women booed louder and the men applauded, and this reversed when she walked offstage. This was a few months after Ozzy’s notorious bat incident in Des Moines, and when he did a trick with birds, everyone started chanting, “Ozzy! Ozzy! Ozzy!”
Oh, oh, i have another one, again in Germany, Müngersdorfer Stadium Cologne, 1994. Top act, ZZ Top. Opening act, Bryan Adams. This was after Adams had that big mighty ballad hit with “Everything I Do”, and of course he had lost any rock credentials with that song. Anyway, ZZ Top fans would have hated him even before that song. So the constant chant throughout Adams’ act was “We want ZZ Top!!!”.
The singer who replaced Rob Halford, at one point, played in two bands, with all the same members. “His” band was basically a hair band that would open for that singer’s JP cover band, and then they would take off their wigs, change their clothes, and do Priest covers.
Joe Cocker opens for The Who, 1969 - pre-Woodstock, barely two months after releasing his first U.S. album.
Oooo. Did Steel Panther sing “The Burden of Being Wonderful”?
I saw The Robert Cray Band open for Huey Lewis and the News. Not sure if that was strange or not, twas a good show, tho.
The time I saw Robert Cray he was opening for Eric Clapton. I got to the arena a little late and didn’t know there was going to be an opening act, so when I heard “Have You Ever Loved a Woman” playing as I got inside I thought I’d missed the start of Clapton’s set. Turned out Cray was just covering it.
I don’t recall.