Someone who condemns a thing but does that exact thing themselves. E.g. someone who comments on an Instagram post "Attention seeking behaviour" implying that such behaviour is to be frowned upon, but in so commenting they have invited attention. Such folks might then get into massive long flame threads if picked up on this, inviting yet more attention. In the end they may have scored more attention than the OP.
A: "Attention seekingbehaviour"
B: "Dude, you're such a hypocrite"
A: "I'm not a hypocrite, you creep"
B: "Are so - you telling me you posted that comment hoping *nobody* would notice? Hypocrite."
An idiot who does things that they tell others not to do and does it themselves because they're brain dead. The worst of these people are those insult the others who do it and then proceed to do the same thing themselves.