Not used often now, but can mean a number of different things:
1 A person who takes bribes from both sides of a dispute;
2 A double-dealer, crook or cheat;
3 A person able to play (musical instrument or sport) with either hand;
Unfortunately Chantale broke her writing hand in a car accident. Luckily for her boyfriend Jeff, she is ambidickstrious and is able to perform handjobs of similar quality with either hand. Had Jeff been the one to have broken his writing hand, he would have had to suffer the consequences of being unable to masturbate effectively for several months.
One who is ambidickstrous is able to Choke the chicken with the right hand while in the shower or spank the monkey with left the hand while on the computer, thus freeing your right hand to use the mouse. Plus it's like knowing two ladies.