I am a fourteen year-old boy and so is my cousin. We are a couple months apart, and we are quite close. Often, when we are alone together, we stick things into each-others asses and give each other anal. We also give each other handjobs and I'm wondering if this is wrong or illegal in australia. We have not told anyone and plan to keep it a secret.
Long story short, it is neither wrong nor illegal.
Basically, there are a few legal precedents for two minors engaging in "normal sexual exploration" activities, and as long as there's no particular power imbalance and anyone can stop when they want without repercussions. In other words, the way you're describing it, it's perfectly fine.