Shrink

[Tofuman]

>From World Wide Words

Shrink, the abbreviation, became popular in the USA in the 1970s,
though it had first appeared in one of Thomas Pynchon's books, The
Crying of Lot 49, in 1965 and there is anecdotal evidence that it was
around earlier, which is only to be expected of a slang term that
would have been mainly transmitted through the spoken word in its
earliest days.

http://www.worldwidewords.org/qa/qa-shr1.htm