Mabel (eating pistachios) - It's so considerate of pistachios that, as they grow bigger, they split open their own shells.
Fernando - That happens when they steam them.
M - They steam pistachios?
F - Otherwise they're poisonous.
M - Well... they should steam walnuts too.
F - I'm just kidding, they don't steam pistachios.
M - (Disappointed that this technology to pre-crack nuts does not exist.) Were you just practicing your Male Answer Syndrome skills?
F - Something like that.
M - ... ... ... I wish walnuts were like pistachios.
VERY IMPORTANT UPDATE!!
Apparently the technology does exist! And yet still no cracked-open walnuts! Surely we can cross a pistachio with a walnut... a walnachio.
When the [pistachio] fruit ripens, the shell changes from green to an autumnal yellow/red and abruptly splits part way open (see photo). This is known as dehiscence, and happens with an audible pop. The splitting open is a trait that has been selected by humans[7]. Commercial cultivars vary in how consistently they split open. (wiki)