In Yu-Gi-Oh! The Abridged Series, the ridiculously stereotypical American Bandit Keith from Yu-Gi-Oh! adds "In America!" to the end of most of his sentences. Parodied in the episode where he duels Joey; as Joey plays Copycat, he declares, "This lets me copy your Catch-Phrase... in America!"
It was also parodied in Keith's second appearance, where during a duel between Joey and Zombie Boy Keith gloats how Joey will be defeated only for the latter to reply "Let me guess...'in America', right?" Keith defensively responds "I wasn't going to say that! ...(inamerica)."
Also, Kemo (Pegasus' henchman, known as the "Nameless Henchman" in the series) constantly begins his sentences with "Attention, Duelists!" and narrates his actions and moods in the third person - but replacing references to himself with his (spectacularly pointy) hair. For instance, "My hair is inviting you to enter the castle!" or "Attention, duelists! My hair is assaulting you!" At one point, Keith and Kemo run into each other...
Same with Mai Valentine, who refers to herself as "My breasts".
Tristan does the same thing with "My voice", though not nearly as often.
Joey very often goes "NYEH!" for no reason, as a sort of sound for all occasions. He himself has no idea he's doing it, and seems not to hear it at all, wondering what Bakura means when he references the Nyeh-sound.
Taken to extremes in one episode where, after being called out on his nyeh-ing, he then proceeds to sing the entire Abridged theme song in nyehs, ending with "Still not hearing it."
Agamemnon Tiberius Vacuum has a weird verbal tic in which his speech is sometimes slowed, sometimes sped up, sometimes even reversed.
Chuggaaconroy says "Whatever" in his Let's Plays a lot, often without him noticing. He tries to cut back on it, but hasn't succeeded.
Mitchell, in the MSF High Forum and MSF High IRC, has an interesting one, in AIM chat and IRC. He tends to surround 'action' posts with '8action8'. This is due to a incorrectly working shift key, which doesn't register his attempt to post '*action*'.
90's Kid also tends to start his sentences with some variation of the word "Dude", while Doctor Linksano has recently begun to trill his R's.
Oh man, look at that raocow and his verbal tics. His tics are such a thing. That's pretty great. Hey there, guy.
Chester A Bum of Bum Reviews has a tendancy to insert 'ma' into the middle of words (e.g. "computer-ma-ter" and Nostalgia-ma Critic).
The Irate Gamer pretty much says "pretty much" and "Alright!" pretty much all the time. Alright!
Pretty much any Minecraft tutorial video is going to include copious amounts of "Like so" whenever they finish doing what they just said they were going to do.
In Ultra Fast Pony, Pinkie Pie uses "bro" as (1) her default form of addressing everyone, and (2) an all-purpose interjection. Note that she has a stereotypical Kiwi accent, so it sounds more like "brew".
Empress says Chumimin at the end of her sentences, which is the same Kiai used by Tusk ACT 4note a form of Johnny Joestar's Stand in Steel Ball Run. When Joseph beats her, he calls her a Chumimin.
Death 13 uses "Rally Ho" in its sentences a lot.
In Noob, Fantöm's tendency to say "I see" is somewhat infrequent after early installments, but gets treated as this by other characters. The tic seems to have popped up due to Fantöm being The Quiet One so he can have something to signal to people with whom he's having a conversation that he's listening to them.
Because they often involve watching reconstructions or listening to audiobooks instead of being able to watch the episodes properly, Who Back When host Ponken will typically review Missing Episodes of Doctor Who by himself, rather than make his co-hosts have to go through them. When hosting alone, Ponken notes he has a tendency to overuse words like "anyway".