"Er" pronounced as "Oi"
From Homestar Runner Wiki
On a few occasions, the "er" sound in a word is pronounced as an "oi" sound, usually spoken by Strong Bad. This is probably parodying Brooklyn accents. Incidentally, Coach Z's and Bubs' accents often causes the inverse to happen which, interestingly enough, sometimes happens in real life as a result of hypercorrection.
 "Er" as "Oi"
- In Search of the Yello Dello — When Marzipan slaps Homestar Runner, The Yello Dello remarks, "Gee, whaddaya think hoi problem was?"
- Email lackey — Strong Bad says "supa soivice" when giving The Cheat a comment on his fast service when he was ordered to get Strong Bad a cantaloupe.
- Email the facts — Strong Bad says, "once again, obsoive."
- Email english paper (DVD Version) — Strong Bad says "what I like to call a little inshoirance" about the money he taped on the english paper.
- Email radio — Strong Bad tells the viewer to "listen and loin".
- Email record book — Strong Bad says to The King of Town, "Nice woik!"
- Teen Girl Squad Issue 5 — The Podcast description reads, "Four teenage girls on Spring Type Break dream of reaching foist base."
- Email your funeral — Strong Bad briefly considers having himself "taxidoimied" when he dies.
- Email from work — Strong Bad says he'd better "get back to woik".
- Email underlings — Strong Bad says he's an "expoit" at dealing with smelly underlings.
- Toikey TV — The title of the toon is "Toikey TV".
- Blubb-O's Commercial — In the Easter Egg, Bubs says he wants "a dang hambloiger".
- Teen Girl Squad Issue 14 — The summary on the TV Time Toons menu reads, "Last day of school for the goyles."
- Email love poems — In a Teen Girl Squad clip in the email, Cheerleader's shirt reads "poifect".
- Strong Badia the Free —
- Strong Bad says "Today, I take over the woild!"
- The King of Town reads an email from "New Joisey".
- Baddest of the Bands — When Strong Bad first talks to Strong Mad in his room, he asks him "What's the woid, big guy?"
- Dangeresque 3: The Criminal Projective — When Bubs as Baron Darin Diamonocle talks to Strong Bad as Dangeresque on the phone, he says that Perducci is passing himself off as an "underwoild informant".
- Career Day — The blocks Homsar stacks on his table read "toid."
- Sbemailiarized — There is a picture of a hamburger, which Strong Bad calls a "hambroiger".
- 2 Part Episode: Part 1 — Gunhaver reads a newspaper named "Commando Obsoiver".
- Where My Hat Is At? (toon) — Strong Bad exclaims "Of all the dumb luck in the woild!".
- Soap Box Doiby
- independent — In the YouTube version, Strong Bad ends with "I gotta go raid Pom Pom's craft soivice table."
- Poker Night at the Inventory — Strong Bad says adopting a strategy of wanton deception is "not the woist idea I ever hoid".
- Strong Bad Reads The Ocelot and the Porridge Maiden — Strong Sad says his wisdom teeth get removed "every summer like clockwoik".
 "Oi" as "Er"
- Decemberween Sweet Cuppin' Cakes — The Wheelchair prepares "berled holiday cabbage".
- Halloween Fairstival — Coach Z serves candy from inside a terlet.
- HomestarRunner.com PAY PLUS! — Cheerleader's shirt reads "sperled rott'n".
- Halloween Potion-ma-jig — Bubs gives Homestar Runner a "terlet brush".
- A Folky Tale — Coach Z claims that Saddy Dumpington's name sounded like a terlet.
- Sbemail 150?!? — The filename spells "149 point 5" as "149pernt5".
- Email unnatural — Coach Z seems surprised that Bubs has a "terlet".
- 2 Part Episode: Part 2 — Gunhaver says the "terlet" is filled with green water.