you teasin’ me, E?! well, I’ll rise anywayz™
I think what ‘s going on here is actually a bit more complicated, though based on tsuwm’s infix observations.
The main sense of this phrase is surely designed to bring out the ‘otherness’ as its basic feature – remarking on how different something is. So buried in the sub-conscious linguistic pattern is our frame of “an ‘other’ experience”, by analogy to “an ‘exciting’ experience” etc.
Yet when we want to express it more forcefully by inserting ‘whole’, we also recognise that we are forced to make ‘an’ agree with it by dropping the ‘n’.
This leaves a taste of incompleteness in the mouth – and when the tip of your tongue finds itself towards the top frontal position dictated by the el sound of ‘whole’, it comes back into mind, requiring you to just inflect the sides of your tongue upwards to form a palatal seal for the change to ‘nother’.
