When I right click my sword, it places a block in my 5th slot. Before I started recording, I made my offhand a fishing rod and it just bugged out, I am not sure what I did exactly, it was just a bug. I then tried with wooden sword and it fixed. I was like wahhhhhhhhh

Also, my video won't upload because of limit, so here it is on mediafire: https://www.mediafire.com/?888d8hq9abua96g

P.S Sorry for background was in skype call
P.S 2.0: I am sorry for the...language used in the video we were laughing at how ridiculous it was, but you guys did say there were going to be bugs so we aren't laughing at you it's just we thought it was funny plz no hate