I have a mouse that has a special triple click button at the tip of the left mouse button. it allows me to rapidly left click in situations where I feel like double clicking with a single button press or whatever. Usually very handy!
It was also handy for finding a very interesting bug on the test server.
Process to recreate bug:
1. click on loot and crafting inventory to get to the hextech crafting area.
2. click the button right above the scrollbar where you can purchase more chests.
3. Click the big 10x bundle button.
4. Hover your mouse over the unlock button and prepare to unleash your clicking fury.
5. Let loose a thousand years of clicking in a mad crazy dash to click that button to death.
result: many bundles are purchased at the same time, I've gotten up to 100 chests and 60 keys at once. (note that these numbers don't match up but THERE YOU GO) see how much you can do.
This is undoubtedly unintended behavior. You'll want to add a warning not to click more than once, due to unintended consequences, before it goes live.