Whenever this creature attacks while you control a creature with power 4 or greater, this creature gets +1/+0 and gains menace until end of turn. (It can’t be blocked except by two or more creatures.)
If you controlled a creature with power 4 or greater when you declared Courageous Goblin as an attacker, it doesn't matter whether you still control one as its ability resolves. Courageous Goblin will still get +1/+0 and gain menace until end of turn.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.