Your landlord can't toss you out for having a keyboard. Your landlord can only get involved if there are complaints from other residents regarding noise levels.
I still advise you to have it fixed. I know you're not from the US, but there are MANY laws protecting renters (actually at times it seems to renters have more rights than the owners).
Have you tried different outlets in your apartment? It's your choice to have it fixed or not. However, you run a pretty serioius risk if this is a severe electrical problem. If you're getting shocked it sounds to me like the outlet isn't properly grounded. That's a bad thing Claudiu!
Squeak
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