316 KB.
	
	
	
		Code:
	
	
		#include <stdio.h>
int main()
{
        while(1)
        {
                printf("Press ^C to exit\n");
        }
}
	 
 
which, for a program that simply loops an infinite number of times while printing an inane message, is still pretty insane.
Perhaps you're thinking of a forkbomb?