Green’s Dictionary of Slang

spam fritter n.

[rhy. sl. = shitter n.1 (1)]

the anus.

personal correspondence: spam fritter – Modern Rhyming Slang for ‘shitter’ (anus). Similar to ‘Gary Glitter’.
[UK]B. Dark Dirty Cockney Rhy. Sl. 95: I had a vindaloo last night and my spam fritter’s been killing me ever since.