noun, noun or participle which takes 'suru'
serious reply; straight answer
Net slang abbreviation of マジなレス (maji na resu). Used when someone gives a serious or earnest response in an online thread, often where a joke or lighthearted reply was expected.
冗談のつもりで書いたのに、マジレスされて驚いた。
I wrote it as a joke, but I was surprised to get a serious reply.
あのスレでは、誰かがマジレスするとすぐに荒れる。
In that thread, as soon as someone gives a serious answer, it turns into a flame war.