The word is a cross between fuck and
phenomenal. It is only to be used when two people engage in sex that is so amazing that the only word to describe it is Phuknomenal. Ways to have phuknomenal sex include,
girl on top,
doggie style and having hair pulled, standing up with your legs wrapped around your partner. You will know you have had phuknomenal sex when you begin to feel your legs shake.