Aaron Hernandez Jail Letter #2 -- I'm Going Nuts Without Internet LOL

Aaron Hernandez is jonesin' for the Internet ... according to a new letter he wrote to a fan.

TMZ has obtained a second letter Hernandez recently wrote behind bars, thanking a fan for a Facebook support page she started ... a page he can't read because jail is an Internet-free zone.

He wrote, "Thanks for the site and sry [sic] I can't check site [sic] there is no internet in jail lol."

Correct ... Hernandez wrote out the word "lol" in pen.

Also, FYI, Hernandez is now aware that his jail letters are making headlines. We spoke to the sheriff at the jail who tells us, Hernandez has been warned to be careful with his letters because TMZ keeps publishing them.