“Some” are racist pieces of shit.
But some ethnic groups embrace their own stereotypes, even the negative ones. So how can someone else be blamed?
With these two comments I’m convinced. Don’t use it.
No, and I suspect you can figure out why, even if you don’t want to admit it
I’ll agree that if Mexicans themselves find it racist, don’t use it. It’s better not to take the chance and offend anyone.
Assuming this follows the usual script, this is the point where you profess to be mightily confused why you’re not supposed to call black people “niggers” because after all, they call each other that. Right?
Well no. I would never use that word, regardless of who uses it.
It’s derogatory.
I’d be questioning, rather, why they themselves use it, not argue that the rest of us should too.
The other thing, what context is “siesta”?
I grew up on the border so this might not apply at all to the interior of Mexico… but I have never known anyone on either side of the border to have a siesta. To me, siesta always seemed Spanish. So if you are referring to the Spanish, then you need a picture of a bullfighter. 
All kidding aside, how Mexican are siestas, anyway?
This is why I want to have your internet babies. < swoon >
And Rihanna’s back with Chris Brown, so he’s off the hook for fucking her up, surely?
How dare people hold me accountable for my own behavior!
I thought of this thread watching the Simpsons this week. The marching band came to threaten Bart and did a formation of him in a noose. Homer asked for a formation of himself in a sombrero. They complied. He then asked for a formation of himself sleeping under a cactus. Instead they spelled out, “That’s racist.”