The Backhoe is the best piece of equipment to use to dig a big hole. Therefore, Backhoe is what you call someone who gets so caught up in a web of their own lies that he is just digging his own grave. Usually this slander is used most effectively by the party being lied to, when he/she catches the 'Backhoe' lying to his/her face.
John: "STFU you Backhoe! When have you ever been to a gym?!"
Chris: "It's true!...I have been"
John: "Ya.. Ok, sure thing Backhoe!"
Can also refer to a tracked machine with a backhoe up front, but is usually referred to as a Excavator
2) A whore that prefers anal sex to vaginal sex.
2): Duncan: Yo man, you get any action last night at the club?
Harry: I didn't get any pussy, but I ran into a backhoe around 11:00 and I gave it to her up the ass for the rest of the night.