Benzylpiperazine (BZP) is a CNS stimulant. It is the most commonly used (abused?) piperazine, producing stimulant & slightly psychedelic effects, Sometimes compared with amphetamine (but producing a far more intense feeling of touch, an MDMA like effect for some).
It also creates the feeling of needing to pee lots.
BZP is currently legal all over the world!
"BZP is used orally at doses of between 70-150 mg. Effects last 6-8 hours" - From Erowid