This "nut" is actually a strange sort of candy made from areca palm nuts, burnt lime and spices, all wrapped in a betel vine leaf. When held between teeth and cheek, it releases arecoline, a mild stimulant that produces a buzz or "high." Even though the central nervous stimulant has generally moderate effects, it is both possible and not too difficult to overdose on it, causing dizziness, vomiting and convulsions.
Frequent use over a long time causes one's teeth to turn red.
Although arecoline is unquestionably a mood-enhancer, it isn't necessarily an aphrodisiac.