Used in place of thought or think.
Whoodah thunk I'd be the one they picked. Or; I guess I didn't thunk it through all the way.

<programming> /thuhnk/ 1. "A piece of coding which provides an address", according to P. Z. Ingerman, who invented thunks in 1961 as a way of binding actual parameters to their formal definitions in ALGOL 60 procedure calls. If a procedure is called with an expression in the place of a {formal parameter}, the compiler generates a thunk which computes the expression and leaves the address of the result in some standard location. 2. The term was later generalised to mean an expression, frozen together with its environment (variable values), for later evaluation if and when needed (similar to a "closure"). The process of unfreezing these thunks is called "forcing". 3. A stubroutine, in an overlay programming environment, that loads and jumps to the correct overlay. Compare trampoline. There are a couple of onomatopoeic myths circulating about the origin of this term. The most common is that it is the sound made by data hitting the stack; another holds that the sound is that of the data hitting an accumulator. Yet another suggests that it is the sound of the expression being unfrozen at argument-evaluation time. In fact, according to the inventors, it was coined after they realised (in the wee hours after hours of discussion) that the type of an argument in ALGOL 60 could be figured out in advance with a little compile-time thought, simplifying the evaluation machinery. In other words, it had "already been thought of"; thus it was christened a "thunk", which is "the past tense of "think" at two in the morning". 4. (Microsoft Windows programming) universal thunk, generic thunk, flat thunk. [Jargon File] (1997-10-11)

In computer programming, a thunk is a subroutine used to inject a calculation into another subroutine. Thunks are primarily used to delay a calculation until its result is needed, or to insert operations at the beginning or end of the other subroutine.

<programming> A software mechanism that allows a Win32 application to load and call a 16-bit DLL, or a 16-bit application to load and call a Win32 DLL. See also generic thunk, universal thunk. (1999-04-05)

<programming, operating system> A software mechanism allowing a Windows 3.1 application to call a 32-bit {dynamically linked library} (DLL) under Win32s. The Windows 3.1 application which wants to call an entry in a 32-bit DLL instead calls a corresponding entry in a 16-bit DLL. The programmer must also include code to detect whether the 32-bit DLL is loaded. A 32-bit EXE loads the 32-bit DLL. See also Generic Thunk, Flat Thunk. ["Calling a Win32 DLL from a Windows 3.1 Application", Win32 SDK Knowledge Base, Article ID Q97785]. [Better explanation?] (1997-10-11)

<programming> A software mechanism that allows a 16-bit Windows application to load and call a Win32 DLL under Windows NT and Windows 95. See also flat thunk, universal thunk. (1999-04-05)