I'll catch you on the flip side -> τα λέμε, τα λέμε αργότερα, δε χανόμαστε, τσάο, τσάγια, τσίου
Generally, "see you later."
The "flip side" is the reverse side of a vinyl record, a term often used by radio DJs. They might say "I'll catch you on the flip side" to mean they will let a particular album play through, and won't start talking again until they have to change or flip records.
"flip flop" is a variant used originally by truckers to mean a U-turn or the return trip, and may be used instead of "flip side."
Catch you on the flip side. I'm a little beat for my doss, so I gotta go float some zees.
http://www.urbandictionary.com/define.php?term=catch%20you%20on%20the%20flip%20side
