Euphemisms or synonyms for plagiarism
How about:
I think Tom's paper was 'inspired' by one he found on the internet!
I also like Reg's 'borrowed'.
Perhaps also:
I see Tom has once again stressed his green credentials, given that his paper was 'recycled' from the internet!
Or [deviating away from synonyms]
Plagiarised? No, I was merely 'paying homage' to [the other author]!
Or
Gandhi said that 'Imitation is the sincerest form of flattery'; I think Tom has seriously flattered another author!
An obvious candidate would be borrowing. A funny-sounding one (at least to me) would be buccaneering.