/jp/ - Otaku Culture

So yesterday there was a "How do I do this in Japanese?" thread on /jp/.
http://archive.easymodo.net/cgi-board.pl/jp/thread/3298471
I couldn't think of the answer then, but I got the answer now, and since some trolls gave the wrong answer to this anon, I hope to help correct it.

To say "I went on a trip with Tanaka as a favor for him", you should use pronouns.
One possible way to say this would have been
私は田中のために田中と旅行してあげた。
It would have been grammatically correct, although repetitive.
To avoid the repetition, using pronouns would make this sentence:
私は田中のために彼と旅行してあげた。
where 彼　is "he".