Episode 1: "NO." shirt

Roy is caught wearing this shirt that simply says, "NO." after feeling down about his recent breakup, in the debut episode of season 4. Say to opposite of "NO." to buying this shirt. "NO." shirt from ThinkGeek

"The Ring" Japan Shirt

The next t-shirt from episode 2 of season 4 features Roy in this red shirt. The design is a tribute to the Japanese version of the Ring. Difficult to find for purchase on the net. Unavailable

Cassette Tape Shirt

This shirt features a cassette tape above skull and crossbones. It reads "Home Taping Is Killing Music". You can grab it today because it is for purchase! Cassette shirt from 8ball.co.uk

Episode 2: 'Orange TV' Shirt

Roy is sporting this blue tee with an orange box television on it in episode 2. I am unable to find this one online, but let us know if you are able to come across it. Appreciate it! Unavailable

ROFL shirt

The IT Crowd brings this ROFL t-shirt won by Roy. There's not much to get with this one. Just purchase it, wear it and being to ROFL.
ROFL shirt from RedBubble

Metallica Parody Shirt

This shirt is a tough one to find. It looks like a Metallica shirt, but not exactly. It looks like the statue of liberty is featured on it, though I cannot make out what the text reads. Unavailable

Firefighter Shirt

This shirt is worn by Roy later in episode 2 of The IT Crowd. Featuring firefighters and the number 451, a reference to the book Farenheit 451 (the degree at which paper will burn). Firefighter Shirt from Enclothe

"I Don't Work Here" Shirt

This is another ThinkGeek shirt appearing on The IT Crowd. Wear this shirt to places you don't work, or have more fun and wear it to places you DO work at!
Unavailable

Episode 3: Time Travelers Shirt

This shirt is for time travelers. Won by Roy in season 4 episode 3 of The IT Crowd. Featuring the essentials needed for time traveling for travelers alike.
Time Travelers Shirt from Topatoco

Music Venn Diagram Shirt

Roy is seen wearing this "Venn Diagram shirt" again in this episode of The IT Crowd. It reads "Music I Like" to "Music I Used To Like" to "Music You Like" from the left to right. Musical Elitism shirt from Diesel Sweeties

Keyboard Cat Shirt

Play him off, keyboard cat. This shirt comes from a popular YouTube video of a cat playing a keyboard. With retro Game Over text, its time to play him off, keyboard cat. Unavailable

Episode 4: OMFG Shirt

This shirt is brought to us by the Ontario Mega Finance Group, a.k.a. OMFG. With a maple leaf and the text, "you won't believe it, eh!" it's a great shirt.
Unavailable

Nothing Is Good Shirt

Roy is caught wearing this shirt from Season 3 again in this episode. It reads, "Nothing is any good if other people like it" - Agree? Then check out this shirt! Nothing is any good shirt via DieselSweeties

Episode 5: Whale Shirt

A wizard has turned you into a whale. Is this awesome (Y/N)? Seen in episode 5 of season 4 in The IT Crowd. Great for adventure game fans.
Wizard Whale shirt from Topatoco

Episode 6: Read E-mail Shirt

The final episode of Series 4 of the IT Crowd shows Roy wearing this shirt that reads, "I read your e-mail." Get it from Thinkgeek.
I Read Your E-mail shirt via Zazzle