cross the line

Short definition from Wiktionary

Verb

1. 1
   To overstep a boundary, rule, or limit; to go too far or do something unacceptable.
2. 2
   To finish a race.
3. 3
   To achieve completion of something.
4. 4
   To cross the equator, as a vessel at sea.
5. 5
   To film from the opposite side of an imaginary axis on set in order to view the actors from the opposite direction.