Former MLB star challenges Alex Rodriguez to take a polygraph over rumors he cheated on Jennifer Lopez

During a vacation in the Bahamas, former baseball player Alex Rodriguez proposed to singer-actress Jennifer Lopez. In a candid photo shared on Instagram, A-Rod kneels down on the beach, offering J-Lo an emerald-cut diamond ring, estimated to be worth $1 to $5 million. Fans were swept away by the rock, and the fairy tale romance.

However, former MLB star Jose Canseco quickly rained on the couple's parade. On Twitter, he accused Rodriguez, his former New York Yankees teammate, of cheating on Lopez with his ex-wife, Jessica. "Watching World of Dance watching J.Lo text Alex Rodriguez little does she know that he is cheating on her with my ex-wife Jessica poor girl she has no idea who he really is," he tweeted.

In subsequent tweets, he added: "I was there a few months back with her when he called her on her phone. Alex Rodriguez stop being a piece of sh*t stop cheating on Jennifer Lopez."

Jose and Jessica Canseco Credit: Getty

Jessica Canseco, who was married to Jose for three years in the '90's, finally broke her silence on the alleged scandal. "Those false accusations Jose is making are not true," she tweeted. "I have known Alex for many years and haven’t even seen him for over 5. I certainly did not sleep with him. I am friendly with both him and Jennifer. As for Jose he can keep playing with his Alien friends."

Confused what Jessica meant by "Alien friends"? Apparently, Jose Canseco believes in aliens. In January, he tweeted, "Aliens have been trying to teach us how to time travel but first we have to change our body composition which we are not willing to do we have tried with animals and it has failed." Then, the following month, he invited followers to join him on a "Bigfoot and alien Excursion."

On Wednesday, Canseco did not tweet any proof of extraterrestrial life, but he did double down on the cheating allegations. In response to his ex-wife's steadfast denial, he wrote, "you lied to defend that piece of shit Jessica I told you to not open up that can of worms time to polygraph and tell the truth now."

The 54-year-old added, "Jessica you're calling me a liar you just forced me to defend myself and tell the truth here comes the biggest story ever about Alex Rodriguez and yourself the truth hurts do not turn away or hide from a polygraph."

Then Canseco turned his sights on the internet's favorite newly engaged couple. "Jennifer Lopez I hear you're a very good person I am sorry you are caught up in the middle of this but the truth has to be told," he tweeted. "Alex Rodriguez I challenge you to a polygraph are you man enough to face me.

He added, "Remember when you told me you were man's man Alex show me now how much of a man you really are face the truth face a polygraph. Alex since you are a man's man why don't you contact me and we'll talk about it face-to-face you know how to reach me."

A polygraph test, aka "lie detector test," measures a person's physiological responses, like blood pressure, galvanic skin response (sweat), breathing rate and pulse. Like you've seen in TV shows and movies, the test begins by asking the subject control questions to arouse baseline anxiety. Then the subject is asked relevant questions, and if they are lying, they will show more anxiety - in theory, anyway.

While polygraph tests are still used by federal agencies and law enforcement, they are not considered very reliable. A practiced liar would not show anxiety, and therefore be able to beat the test. Sometimes they're accurate, sometimes they're not, and this is not news. Yet despite their contested accuracy, the popular devices remain part of the theater of interrogation.

But hey, maybe Jose Canseco got a special polygraph machine from the aliens that is 100% reliable.