Sometimes the calculator detects that an equation is too complicated to plot perfectly in a reasonable amount of time. When this happens, the equation is plotted at lower resolution.
Unresolved Detail In Plotted Equations

Bob Deen Pretty sure I broke the universe
xyxyxyxyxyxyxyxyxyxyxyxyxyxyxyxyxyxy=yxyxyxyxyxyxyxyxyxyxyxyxyxyxyxyxyxyx

David Summa For x!! = y!!
I feel like its trying to communicate with some weird cryptography.

chris Russ sin(xy) = x/y is wierd too O.o

Ezra Seidel Ah yes, the Crispy/Browning Rice Function. Its graph is very interesting.

Bob Deen I heard it's been quite useful in one of Einstein's lesser known theories, the theory of relative burntness.

Seth Upperman x^y+y^xsin(x)=a

Seth Upperman sin(x^2y^2)=a (a cannot be to large of a value)

Hank Witaker x=((sin y)/(sec x^y))y

Scott “x” Blair 0 = $a\sin \left(x^2+\cos \left(bx+cy^2e\right)\right)+dy$ make the variables change

곽성재 A chessboard with circles: $\left(\sin x\right)!=\left(\cos y\right)!$

Scott “x” Blair 
Juan Moreno x=sin(cos(x*tan(y)))

Andrew Myers If this happens to you, try relplot instead. It is not as interactive, but it will plot everything.

lin kaixuan Sin(x^2)+sin(y^2)=0
The equation looks ok but the graph is all over the place 
Samybencherif $y^2x^3=\cos \left(x^{2y}\right)$
negative x axis is something to speak of.. Not sure if it's due to "noise" from low resolution graphing or the graph itself

Parker Mowery 3pi*sin(x^y)=y does it before you zoom out. So much lag.

Ezra Seidel $\tan x^5=y^5$

Ezra Seidel $\gcd \left(x!,x!!\right)=y!$

Anders UrbergCarlson This will destroy the world:
tan(x)+tan(y)=tan(xy) 
Harry Harrison x^sin(y) = y^sin(x) is still very cool despite this error.

Parker Mowery How about $y=\frac{d}{dx}x^23\sin \left(xy\right)$

Harry Harrison The simple ones are the best. Enter y = (x^y)*sin(y^x). This community of crazy graphs is one of the best corners of the internet.

Cameronho2015 $\frac{3}{\sin \left(\tan \left(\sec x\right)\right)}=\frac{7}{\cos \left(\cot \left(\csc y\right)\right)}$

Harry Harrison $\frac{d}{dx}\sin \left(x^y\right)=\tan \left(y^{\tan \left(x^y\right)}\right)$

Dylan Honors $\lcm \left(x,4y\right)=\mod \left(x,4\right)y^2$

G Money cot(xy)=2

Стилиян Петров or maybe sum a n=0 *1^nx^2n+1/2n+1!*sin(y!

Стилиян Петров Try it!

Jplantiko i think i found a glitch in the matrix
https://www.desmos.com/calculator/s2qpe42anl 
Pedro Gómez press play and see the magic https://www.desmos.com/calculator/hx9tk1yh5l
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