Tyga -- I'm About to Catch a Felony ... Statutory Rape-y Rap?

3:00 PM PT -- Tyga says the song is almost 2 years old. He was still with Blac Chyna back then, so he seems to be saying "Pleazer" has nothing to do with Kylie.

Tyga just released a sultry, romantic song about his GF Kylie Jenner -- nah, just kidding ... he's actually dropping a rap about illegal sex ... y'know, like with a 17-year-old.

Tyga does not shy away from the obviously sensitive issue with his new song, "Pleazer" ... 'cause the 25-year-old included these lyrics:

I hit her, she backwards, lickin' her a**hole
My d**k is the password
T nasty, 'bout to catch a felony for it
Vagina juice like orange juice in the mornin'