In another thread this came up as a passing thought.... 

What are the weirdest band lineups you have ever seen?  

Philadelphia Mummers in full costume open the show.... 
Gary Wright of Dream Weaver fame with 5 keyboard players and a drummer 
Peter Frampton with his Come's Alive album show
Yes.... headlining with all their classic hits to date and new stuff

Quite the mishmash of styles and genres

my second entry to this category of weirdness: 

Poco: country rock band opens for
Blue Oyster Cult second on the stage
Johnny Winter headliner. 

Poco, got booed off the stage after 2 or 3 songs. Johnny Winter reprimanded the audience for booing Poco. 

We did this before I think..... anyway

For me - Los Angeles Forum

Cat Mother and The All Night News Boys*
Chicago Transit Authority (later to be simply known as Chicago)
Jimi Hendrix



*Cat Mother was produced by Jimi and was so unlike Jimi in every respect


Another was as the Pasadena Rose Palace (not as exotic as it sounds, it's just a huge square building with a stage and no seating).

Brian Auger and Trinity
Elvin Bishop Blues Band
The Chambers Brothers
Led Zeppelin

What was even stranger was that the full lineup did two full sets each.
(Note: at the time Led Zep II was not released and I heard early versions of Heartbreaker and Moby Dick.)

Hendrix and The Monkeys.

Dire Straits opening for Talking Heads was the oddest one I've seen.

There are some famous ones - Hendrix opening for The Monkees, Kool and the Gang supporting Van Halen..SRV opening for The Moody Blues..wtf?

Bapsi.... getting old has it's ups and downs..... one of those is memory tends to fade a bit. I was thinking we might have had this convo before..... but..... uhhh, what was I saying...?



Oh never mind.... 

It's just that the ups and downs get harder to do as you get older...

Tom Petty and the Heart Breakers opening for Meatloaf. Meatloaf blew em away !!
 
Ticket price was $5.00.
 
 
 
.

One of the coolest pairings I've seen was Jeff Beck opening for Santana....Jeff Beck blew us away then Santana blew everybody away with a fabulous set. Coolest show ever !!

I saw The Proclaimers in Dubai a couple of years ago.

The venue management insisted that the two resident cover bands play AFTER the Proclaimers finished their set.
 
I was talking to the singer of one of the band's, a Filipino hard rock cover band, and she said they were not at all happy with having to follow the headline act.

The other resident band came on directly after the Proclaimers and immediately launched into their crowd pleasers "Smoke on the Water" and "Shine on you Crazy Diamond" with a no prisoners taken attitude that promptly achieved the management objective of keeping the majority of the crowd from leaving.
 
In years to come both bands will of course be able to recall the time when The Proclaimers opened for them

Keith Richards playing bass and John Lennon playing lead in Rock 'n Roll Circus. The same film features Tony Iommi playing with Jethro Tull.