～ついでに

About

ついでに is a combination of the noun 序ついで, "opportunity; occasion; chance", and the に particle.

ついでに is used to indicate that a subject does auxiliary action Y, while doing main action X, in the pattern: 「XついでにY」.

ついでに attaches to casual form verbs, and to nouns with の (which is sometimes dropped).

E.g. 出張しゅっちょうで大阪おおさかに行いくついでに、友達ともだちにも合あう。 "While I go to Osaka for work, I'll also meet with my friend."

ついでに is nearly always written in kana.

ついでに sentences often have the English approximations, "While doing X, also did Y", or "Did X while (I'm) at it".

In a ～ついでに sentence, both actions are completed by the same subject.

ついでに can be used as a standalone phrase.

E.g. コンビニ行いくの？ついでに郵便局ゆうびんきょくよってこれ出だしてきてくれない？ "Are you going to the convenience store? Would you mind mailing this at the post office while you're at it?"

ついで can be used as a standalone noun.

E.g. ついでだったから、シャンプーも買かってきたよ。 "I got some shampoo as well (while I was out/shopping/etc.)."

Summary

• 

  ついでに is used to indicate that a subject does auxiliary action Y, while doing main action X, in the pattern: 「XついでにY」

• 

  ついでに attaches to casual form verbs, and to nouns with の (which is sometimes dropped)

• 

  ついでに is nearly always written in kana

• 

  ついでに can be used as a standalone phrase or noun