Means: When a pupil (typically male) talks to a fellow pupil they find attractive with non-platonic intent, often tirelessly.
Usage: "Did you see Dom sharkin' Melissa last night?"
"Chatting up" and "chirpsin" may be more unisex ways of describing the early moments of the modern courtship ritual, but "sharkin'" is a term usually reserved for the male of the schoolyard species. Based on the aggressive, relentless hunt of its water-based namesake, it often involves house parties, darkened corners and the climax of: "Can't you take a hint?" But if you find it hard to think of little Dominic so sexually aggressive so young, be thankful you're not teaching English as a foreign language in Japan. There, "sharking" is the term for the unsavoury yet popular practice of pulling down a girl's underwear in public. Which makes a little over-zealous, "So you like the new N-Dubz album?" seem positively proper.