This=That
This=That is an esoteric programming language by User:PuzzleHunter84, and is made up entirely of variables. Each line is just a casesensitive variable name, followed by =
, and then the variable's casesensitive value.
The variable names can be anything including special names, and the values can be anything as well, and can also be special values:
print 
prints the variable's value. 
input 
inputs a value for the variable to take. 
plus

do math. For example:
x=4 Jerome=x minus 2 sets fruit=fly printer=paper sticky=fruit plus printer sets 
if loop x=condition 
starts an if loop named x with the given condition.

while loop x=condition 
starts a while loop named x with the given condition.

if loop x=end

signifies the end of if /while loop x .

Conditions have three parts, two compared values referenced by their names and a comparison which can be:
> 
is greater than 
< 
is less than 
~ 
is not equal to 
~> 
is no greater than 
~< 
is no less than 
~~ 
is equal to 
Example programs
Hello, world! Program
x=Hello, world! x=print
Cat Program (Until QUIT is inputted)
x=input while loop y=x~QUIT x=print x=input while loop y=end
Endless Bottles of Beer Program
a=99 b= bottles of beer on the wall. c=a plus b d= bottles of beer. You take one down and pass it around. e=a plus d f=c plus e g= bottle of beer on the wall. h=a plus g i= bottle of beer. You take it down and pass it around. j=a plus i k=h plus j l= bottles of beer. You go to the store and buy some more. m=a plus l n=c plus m o=0 while loop x=o~~0 while loop y=a>2 f=print a=a minus 1 c=print while loop y=end f=print a=a minus 1 h=print k=print a=No c=print n=print a=99 c=print while loop x=end
Endless Fibonacci Program
a=0 b=1 a=print b=print while loop x=b>0 a=a plus b a=print b=a plus b b=print while loop x=end
Endless Square Numbers Program
a=0 b=1 a=print while loop x=b>0 a=a plus b b=b plus 2 a=print while loop x=end
or
a=0 while loop x=a~<0 b=a times a b=print a=a plus 1 while loop x=end
Simple Adding Machine
x=input y=input z=x plus y z=print
Digital Root Calculator
a=input while loop x=a>9 a=a minus 9 while loop x=end a=print
Counts down from inputed value to zero
a=input while loop x=a~<0 a=print a=a minus 1 while loop x=end
Counts from zero to infinity
a=0 while loop x=a~<0 a=print a=a plus 1 while loop x=end
Computational Class
This=That is Turingcomplete, because a version of brainfuck without I/O, with tape length 3 and in which all loops are balanced (i.e. the location of the tape pointer is constant for any given byte of the code) can be compiled into it. (This is in turn known to be Turingcomplete as it can implement an iterated Collatz function.)
Use three variables (e.g. a
, b
, c
) to represent the three tape elements. The brainfuck commands can be implemented as follows:

+
:v=v plus 1
(where v is the variable representing the pointedto tape element) 

:v=v minus 1

<
,>
: these don't directly produce any code (rather, they change which variable is used in+[]
) 
[…]
:while loop x=v~0 … while loop x=end
(where x is different for each such loop)