Considering he's unable to date his mother, Shia has admitted to liaising with members of the opposite sex which he's not related to. One such individual was Rihanna, who he reportedly asked out on a date while he was filming Indiana Jones and The Kingdom of The Crystal Skull, but it didn't work out. Probably because he's not violent towards women.
"(I was) filming a sword fight when I got the message. I said to myself, 'Can this be my life?' (weeeeell, getting a text off Rihanna about a date after wielding about a mighty sword is more normal than you and your teenage mates looking at your mother playing naked connect the dots...) It never got beyond one date. The spark wasn't there. We weren't passionate about each other in that way (again, the no threat of physical danger thing), so we remain friends."
Someone Shia did enjoy a spark with, however, is Megan Fox. Funny that. Seemingly they were all tingly in special places during the filming of Transformers:
"We were very smart (?!?). We're attracted to each other (well, one of you definitely is), and I think you can see that in our scenes together. It's very real and tangible, and you can tell something exists. We could be shooting, and the relationship is suddenly on the rocks and then what? So we just never did anything about it."
Yeah, that's why you didn't get it together. Megan's boyfriend/fiancee/boyfriend of five years, Brian 'David' Austin 'Silver' Green, will be happy to hear she managed to restrain herself due to possible awkwardness on set if things didn't work out between you two horny lovebirds.