see you	CU
wait	w8
be right back	BRB
in my humble opinion	IMHO
in my opinion	IMO
away from keyboard	AFK
as far as I know	AFAIK (o ile wiem)
by the way	BTW
end of topic	EOT
frequently asked question	FAQ
lots of laugh	LOL
ok	K
please	PLS
not applicable	n/a (nie dotyczy)
itd.	etc.
number	no.
for example	e.g.
postscriptum	P.S.
thousand	K (z cyferkami)
with reference to	re (w nawiązaniu do)
very important person	VIP
value added tax	VAT
street	st
that is to say	ie (to znaczy)