En una de las lecciones de este sitio:
Affirmative informal (tú) commands {Beta}
Se dan los siguientes ejemplos:
Pronoun placement: the pronoun is attached to the end of affirmative commands and the verb carries a tilde to maintain its original stress. • Tráemelo. (Bring it to me.) • Dígasela. (Tell it to her.) • Cómpraselo. (Buy it for him.) • Ponte los zapatos. (Put on your shoes.)
No creo que "dígasela" sea un mandato informal, sino un formal:
dígaselo 1. Compound of the formal second-person singular (usted) imperative form of decir, diga and the pronouns se and lo.
[enter link description here][3]
díselo 1. Compound of the informal second-person singular (tú) affirmative imperative form of decir, di and the pronouns se and lo.
Quisiera saber si tengo razón en esto o no.
[3]: http:// http://en.wiktionary.org/wiki/díselo