what is the best and fastest way to relieve menstrual cramps

Lay on your tummy with a heating pad under your tummy. That's what i do.

have sex. lol

ive never been able to do that during the time of the month

Heating pad, warm shower or bath but take a Advil first normally by the time your done your cramps will have at least subsided.

Sex.
Ibuprofen

I take a hot bath, followed by strong pain meds and meditation, plus resting. I get them so bad that I have prescription pain meds. I can't even get out of bed when mine come.

Pamprin or Midol

Masturbation until orgasm can help. Taking a hot bath or shower. Using a heating pad or something warm on your lower abdomen. Medications such as Tylenol, Midol, Pamperin, (just remember, everyone has a different biochemistry so what works for one person, might not work for you) Tiger Balm patches are pretty wonderful. They're a topical pain reliever and they use heat to relax. You can get them at wal-mart. They are near the joint creams and such are.
Exercising and walking.
It just depends upon what works for you.
If your cramps are very painful where over the counter medication isn't relieving your pain, you should go see your doctor because something else might be going on.
Best wishes!