Yeah yeah yeah: 1. Yes. 2. Irritating way of seeming to acknowledge what the other person is saying, whilst actually patronising them, as in “Yeah I get it you dickhead, now move on to something more interesting.”

Jump on a call: 1. Join a conversation on the phone. 2. Strangely energetic phrase suggesting that stringent physical action is somehow involved in the simple business of having a chat; a close cousin of jumping on an email, which sounds positively inadvisable.

BW: 1. Best wishes. 2. Pretty much pointless pair of letters used on email when it would have been just as easy to write best wishes. (see Bz; IMHO; KR; PCB; Tks)

Bz: 1. Busy. 2. Mindless abbreviation of an already-short word, just in order to save writing two letters. (see BW; IMHO; KR; PCB; Tks)

IMHO: 1. In my humble opinion. 2. Seemingly innocent four-letter acronym that usually precedes a splenetic burst of invective in an overlong email. (see Enlighten me; TBH)