[masaegu]

Let me introduce a quote from an outside source in hopes of bringing in some objectivity into the matter.

"Otaku is derived from an honorific Japanese term for another's house or family (お宅,　御宅 otaku) that is also used as an honorific second-person pronoun (roughly equivalent to usted in Spanish). The modern slang form, which is distinguished from the older usage by being written only in hiragana (おたく) or katakana (オタク), or rarely in rōmaji, appeared in the 1980s. It appears to have been coined by the humorist and essayist Akio Nakamori in his 1983 series An Investigation of "Otaku" (『おたく』の研究, "Otaku" no Kenkyū?), printed in the lolicon magazine Manga Burikko,[1] who observed that this form of address was unusually common among geeks and nerds. It was apparently a reference to someone who communicates with their equals using (unnecessarily) the distant and formal pronoun, and spends most of their time at home.[1]

The term entered general use in Japan around 1989, and may have been popularized by Nakamori's publication in that year of The Generation of M – We and Mr.Miyazaki (Mの世代－ぼくらとミヤザキ君, M no Sedai – Bokura to Miyazaki-kun?). It applied the term to the (then) recently caught serial killer Tsutomu Miyazaki, who turned out to be a recluse obsessed with pornographic anime and manga and who lived out his rape fantasies on young girls, thus attaching a huge taboo to a formerly innocuous term."*

* Wikipedia

I'm not going to tell you what kind of a T-shirt you should or shouldn't wear. All I want to say is that I personally don't like that particular message. It's different from saying "I'm a proud Otaku" as you actually seem to be one.