The context was @ing someone in with abuse, which clearly falls under the malicious communications act.
You haven't said why it is clearly a joke given that context.
(, Fri 10 May 2019, 16:54, Reply)
There's no threat there. There's no profanity. According to case law it would not be considered grossly offensive. The only thing it actually contains is an implication that she's ugly. I think you'd need some pretty interesting chicanery to actually classify this as abuse from a legal standpoint.
(, Fri 10 May 2019, 17:05, Reply)
your neighbours' letterbox with his joke on them. See how you get on.
(, Fri 10 May 2019, 19:18, Reply)
doesn't mean it isn't a joke. Your face for example.
(, Fri 10 May 2019, 19:28, Reply)