tell on

tell on  {v.}
1. To tire; wear out; make weak.
The ten-mile hike told on Bill.
2.  {informal}
To tell someone about another's wrong or naughty acts. — Used mainly by children.
Andy hit a little girl and John told the teacher on Andy.
If you hit me, I'll tell Mother on you.
Categories: naughty {informal} {v.}