Tiffany is a hot brunette teenager, from the episode Camping Ain't Easy, who Woody falls in love with after discovering her at the summer camp, and not knowing her age at first, until Ethel takes her to the Rich Kid Camp. Because she is nearly 18, Woody attempts to have sex with her.
Unfortunately, a guy named Chad tries to win Tiffany's affections which enrages Woody to the point where Woody tattles on him with his parents, angering his parents, and Chad is defeated. Afterwards, Woody and Tiffany have sex, which results in Tiffany becoming permanently paralyzed since Woody's thick long penis has broken down her legs in the intercourse.
Later on, Woody finds out Tiffany is actually his biological daughter because Tiffany's mom, Sharron mentioned that they had unprotected sex 18 years and 9 months to the day. Woody becomes disgusted he just committed incest and gets angry at his penis for having made him screw his own daughter.
There's a chance Woody got Tiffany pregnant just like with Sharron.