Hilarious' "Lamborghini Member" and mprep's "Diamond Member" is poking fun at the Copper Member rank that was introduced a while back.
As you can see, custom titles show at the same place as the "Copper Member" text when people are posting (not on a users profile).
I would assume rickbig's "I'm not a member" is meant in a similar way.
My original custom title was Gold Member. Mprep then one-upped me with Diamond Member, so I had to go one further and become a Lambo member.
Someone ask hilariousandco how to get lamborghini member custom title and hilariousandco replied that in order to have a custom title you have to donate btc and pm theymos about it.
Well, that's how you become a donator which will give you the option of a custom title. I might have joked in the past that if you buy theymos a lambo he will give you that title though.
what's the difference with the others, is there any special effects or is it just a regular title?