"like" and "as if"

[Arnold M. Zwicky]

from Garry Tudeau's Doonesbury strip of 6/21/05:

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A:  So basically you're quitting your job to go to a party.
B: Oh, like you've never done that?
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here, "like" + clause is punctuated as a question (presumably with a
rising final intonation), but a somewhat more assured response would
use an assertion.

"as if" can be used in a similar way.

i don't recall having seen any treatment, synchronic or diachronic,
of this construction.  if it's alluded to in the OED, i haven't found
it.

then, of course, in the next step, "as if" can be used by itself,
without a following clause, as we discussed here in a thread a while
back (which has since drifted to other things).

arnold (zwicky at csli.stanford.edu)