Disgruntled -> gruntled
Unhinged -> hinged
Overwhelmed/underwhelmed -> whelmed Discombobulated -> combobulate Disghust -> ghust
Them: "How'd you like that new burger joint Bad Jimmies? I heard it's amazing!"
Me: "Not bad, but I found their burgers to be...[0] whelming."
0. The pregnant pause-for-effect is very important here, since it makes even the use of "whelming" a whelming experience.