As fun as this sounds, you could be giving someone a really bad day. Bitches be crazy and only see red. So when the guy in the relationship is telling ol' bitchy "I don't know what you're talking about" she'll likely not believe him, and depending if the situation and health of the relationship, you could be ruining someone's night you didn't intend to hurt, or worse, end a relationship.
Now that I explained potential consequences, if I had no remorse, I'd just go along with the charade and reply with something like "But he likes it when I text him"