Some one who if they can't have something destroys it rather than letting some one else have it. From the to common habit of some I.T. people of destroying decommissioned equipment, instead of putting it in recycle. A update of a dog in a manger.
What's the difference between an I. T. guy in a manger and a dog? The dog eventually leaves , and the other animals get use of the manger, the I.T. guy pisses and shits in it so on one can use it.
A 'French' term typically defining a sexual liason between three persons, involving three people engaged in sexual intimacy or sexual congress. Three people having sexual relations with one another either randomly, such as on a one-time occassion, or regularly as long-term lovers. Three people having sex together, typically at the same time in the same bed.
A favorite fantasy of men- that of being in bed with two women instead of just one- but women also imagine bedding for sexual purposes with two men. Such is also known well enough between three lesbian women, or between three homosexual men. As long as three people are intimately/sexually involved, it is a 'manage-a-trois'.