No digues mentiras. Correct Incorrect
Answer : Incorrect.
Explanation : There is no verb tense in Spanish with the word "digues".
You could want to write the second singular person in the present in indicative mode of the verb "decir" = dices. "No dices mentiras" that means You do not tell lies.
You could want to write the second singular person in the present in subjunctive mode of the verb "decir" = digas. "No digas mentiras" that means I hope you do not tell lies.
You could want to write the second singular person in the present in imperative mode of the verb "decir" = digas. ¡No digas mentiras! that means I command you do not tell lies.