Something unexpected, confusing, out of the ordinary. When a person is expecting one thing and then something else happens.

"Yo, she threw me a f**kin rhombus!"

In this case, said person recognizes that a situation became compromised, and then states loudly that the offender did something out of the ordinary by throwing her an unexpected shape of sorts.

A portion of the Princeton Univeristy campus used for smoking weed. Phish smoked there back in the day, too.

ok - the REAL definition of a rhombus is this:
n(primarily used in the UK): one or several nights of hard DRINKING and/or DRUGGING that leads to a loss of memory, a laundry list of offences, multiple contusions and/or lacerations to the face and body, and in rare cases - illegitimate children.
the Rhombus is not to be taken lightly - and is most often presented as an agreement between two parties in accordance with the plans for the evening(s)

a large male, usually one whom is the dominant male in a prison, or other group of men. Typically one whom makes others his bitch.

Any asian girl's pussy

The act of 4 guys simultaneously humping someone from 4 sides. Originated when a "wtf eiffel tower" was performed with an extra person. Can also be used in place of "owned" or "raped" in modern sentences.

Female reproductive part.