A jack off buddy (from 'cum' /'come', meaning 'semen', and 'companion'); a friend that you get together with for sessions of solo or mutual masturbation
Variant of: cumpanion (from 'companion' & 'cum'); jack off buddy & wank bud & JO buddy
Similar to: fuck buddy

Used when you want to say the same thing in return to someone, but you can't be arsed to type the full thing. Means 'same here' pretty much.

it seems nobody got the real source yet:
'Ditto' comes from Latin, and means about 'as has been said before'. So most of the other explanations are correct.

1. Also, or the same

2. A purple/pink transform Pokemon that looks like a blob.

ditto mark: a mark used to indicate the word above it should be repeated
repeat an action or statement; "The next speaker dittoed her argument".

The word "ditto" is commonly used as a way of saying "me too", or "I agree".

Worst word in the english language. It is the laziest word, it is just an excuse not to respond properly.