Why did I get yelled at for entering? All I did was put out my intro!

Intros are an often used, frequently abused "shorthand" for describing your character in Ayenee. Properly done they're informative and somewhat entertaining. Improperly done they're spamming and annoying.
However, the problems with using an Ayenee intro in WoD are numerous. One, some folks consider it a little cheap, and thus tends to get a little groaning from time to time. Two, actions that are acceptable and even expected in Ayenee are totally inappropriate to World of Darkness.
Entering a room in WoD by teleporting into the middle, flashing your fangs and declaring "Dark eve, all" will get you outright laughed at, sorry to say - for two reasons. First of all for the use of powers that don't exist in WoD. While there's some teleportation like effects for vampires, they don't generally work that way, and using them for an entrance in a WoD room doesn't impress the other players with your originality - it impresses them with the fact that the character doesn't fit with the rules they've all agreed to play by.
Any display of superhuman physical structure (like wings, tails, tentacles, horns, whatever) will also be met with a strong amount of skepticism. Remember, the superhuman races of the WoD hide what they are from a currently-disbelieving populace. Even added all together, the supernatural races/character types of WoD are grossly outnumbered by the normal humans, and could pretty easily be wiped out if they were foolish enough to reveal their existence to the normal humans. A vampire who flashes their fangs and makes it clear that they are a bloodsucking member of the undead is asking to be staked and killed by their own kind, far before anyone human caught on and tried the torches-pitchforks-an-mob-of-angry-villagers routine. A shape-changer who shows what they are to normal humans is breaking their "litany" and is asking to be hunted by their own kind. Mages are highly affected by paradox, which comes of - guess what - the normal humans seeing the mage do magic.
Remember that the WoD setting is modern and mundane - if a little darker than our world - and it's not really that far off from where you might live. Such blatant acts as carrying visible swords or guns would get you stopped by the cops in our world - and thus it would happen in the WoD too, only the cops of WoD are likely to arrest you out of hand - and fire if you choose not to cooperate.
Before you yell at me for being a snob, let me explain that the first character I ever brought into the Yahoo! World of Darkness rooms was much the sort that I've just been describing. Visible weaponry, outlandish clothes, etc. I blush to remember it - and I altered her easily, so she fit in with barely a ripple. It can be done, without damaging the character beyond repair, trust me. I did it - so can you.
All you need if you want to do an intro in WoD is a) an appropriate character with sheet, b) a description for the character that doesn't include visible weaponry (note I said visible. if you want to note weapons so someone doesn't think you're just making stuff up on the fly, go ahead. Describe it as concealed - and make people roll to see if they sppot the hidden weapons, if they try saying they spot it without trouble) or unconcealed non-human body types, and c) acknowledge the setting (don't say "walks into the room" if the "room" is a full-city setting - that's the first things people jump on.) Observe those rules, and nobody will yell anything but "ooh, cool"