瞎 here doesn't mean 'blind' — it's an adverb meaning 'recklessly / pointlessly / blindly' that prefixes verbs to suggest 'doing X without sense'. So
瞎闹 = 'making noise/trouble for no good reason'. Same pattern in
瞎说 (xiā shuō, talking nonsense),
瞎搞 (xiā gǎo, messing around),
瞎想 (xiā xiǎng, thinking pointless things).
