what have I done?

[canetoad]

2. Hi Kali

Keyboard might be buggered - it happens. Is it a gaming keyboard? They are usually programmable and you may just have lucked out with the key combination.

Could also be junk, dust, cannabis seeds (joke) or other detritus down between the keys. Upend and tap gently until stuff falls out or use a can of air duster to clean.

I go through keyboards like chocolates and always keep a couple of spares. If none of the above works best to try a new one.

Edit: Forgot to say: did you happen to get any liquid on it? Only a drop will do in the right place. That can cause freaky behaviour as you described. Solution - turn upside down and let it dry out for a day or two.