Irregular "tú" Commands
The following eight verbs have irregular familiar commands in the affirmative:
Note that these irregularities only occur with affirmative tú commands. As with all other verbs, to form negative informal commands with these verbs, use the “tú” form of the present subjunctive.
Di la verdad. (Tell the truth.)
No digas mentiras. (Don’t tell lies.)
Haz tu tarea. (Do your homework.)
No hagas eso. (Don’t do that.)