When CHARLIE SHEEN gave LINDSAY LOHAN $100,000 to pay down some of her debt to the IRS, he didn't expect anything in return.  Except maybe a "thank you".

--He says, quote, "[She's] a very good and decent young lady that is just going through a lot.  I'm still waiting for a text to say 'thank you.'  Anything, you know?"

(--Meanwhile, TMZ has some pics of Lindsay in the front row at the Wanted show in New York City on Friday night.  Check 'em out here.)