Yes okay so I know I'm going to get a lot of hate for this but one time when I was in first grade I don't know why but I took my friend's pencil box and threw it away. No one in my class knew and we spent a whole week looking for it and I was freaking out that they would find out that I threw it away. Eventually they gave up so my friend had to use a Ziploc bag to hold his school supplies.
Since this day they've never known I threw it away.
Once stole £80 (over like 2 months) out of a jar full of coins and notes! and my parents found out they grounded me and said it was out my own Christmas money they have been putting away for xmas ... the backfire! I was 13.
No one in my class knew and we spent a whole week looking for it and I was freaking out that they would find out that I threw it away. 
and 1-2 times money from my parents/sister 
not a big amount tho.