愉 pleasure

This tanoshii means the same as the OTHER tanoshii (楽しい), except that 愉しい is very literary and pretentious.

Basically the only time you'll see 愉しい is if your friend is typing on his cell phone and the "auto-complete" feature selects this one instead of the usual one. However, that happens a lot in today's troubled society, so it might be worth your while to learn 愉しい. (As a matter of fact, there's a LOT of kanji that only occur as a result of auto-complete snafus. Older folks who complain that the internets is making young Japanese kind of illiterate and culturally myopic should be thanking auto-complete - it's responsible for accidentally reviving a whole CLASS of old words! )