It sounds like your office likes blocking IRC. It makes sense. It's distracting.
Method 1: Using a VPN
Proxies/VPNs are the greatest friends of students and employees trying to skip content filtering systems. However, many places have policies against using proxies/VPNs which can get you suspended or fired, respectively. I AM NOT RESPONSIBLE FOR JOB LOSS. There are many ways to implement a proxy/VPN:
Method 1a: Using a Rented/Free VPN
Many times, you can just use a rented or free VPN to do the job quickly and easily. Simply find one you like, type it in as the system VPN (network settings), and you're good to go! Some good ones I've heard about are FreeVPN.me and VPNBook. Your milage may vary.
Method 1b: Using your home PC
If you have server skills, you can set up a VPN at home to host stuffs. However, this may cause issues. Namely, slow internet and packet loss. There are many ways to do this, and there are too many to list here. Google "How to host a vpn server ubuntu" and you'll get ~730,000 results.
Method 1c: Using DD-WRT
If you have DD-WRT, you can set up a proxy server at your home. The relevant options are under
Services > VPN. Choose PPTP or OpenVPN, they both work well at giving you your IRC fix.
Method 2: Find a way around
Most places I've worked or learned only had hostname/port blocking. Try using weird port numbers that are allowed, as well as using IP addresses. There is usually SOME combination that works. (My old school completely blocked HTTPS after seeing how that allows you to jump out of the filter).
Method 3: Visit your SysAdmin
Chances are, your sysadmin is human. You can go talk to him and try to get him to unblock IRC. He might just do it. Also, most IT guys are suckers for free lunches. Bring him a lunch. You'll be on his good side FAST. IT guys are usually nice anyways. Your mileage might vary though.
Method 4: Online IRC
Just use a web-IRC client. No software, no mess. And the best part is, you can just use those free online proxies to get at em.
Method 5: STOP COMPLAINING
There is obviously a reason why IRC is blocked. Just do your work and get your paycheck. IRC at home.