Amazing Spider-Man 591: Unthinkable!
This is how the comic opens:
ARG!
The Headless Spider-Man!
If you didn’t catch Issue 590; Spider-Man was given a blank checque, made out to Cash to join the FF on a journey to the “MacroVerse” in response to a summons from the (formerly) grass hut living primitives there.
Johnny got it up his nose to see what was under the mask of the mysterious Spider-Man and THIS is what he found. Eeeeeww.
Without giving away too much, time is compressed while they are in the Macroverse and about 13 and 1/3 days go by (about two weeks, sheesh). This is a nice way to move time forward in the Spidey-Verse so that things can go down.
Something goes down that makes Spider-Man react like this:
Oh, No! Aunt May is Dating Dr. Octopus AGAIN!?!?!
Actually; no. It’s not Aunt May. It’s something much more horrifying to Spider-Man (even worse that Osborn as President!?!?!?) you’ll have to check out the issue to find out, I promise you’ll enjoy it.