I am asking for a niece.
Her BF bowls in a Mixed League. It requires two males and two females per team. Each team sets itself up (members are not assigned). The new team member who came on as a replacement and is "partnered up" with her BF has a special "good job" gesture she uses with niece's BF. BTW, the BF is long time BF who is engaged to niece and is her SO.
This is what is done instead of a high five (done for strikes or spares made) or a fist bump (done for spares not made).
She just slowly slides her fingertips and palm across his palm and then fingertips - as he is doing same with her. They do whether it's a situation calling for high five or fist bump. She - and he - gives other team members (there are 4 to a team) high fives and fist bumps as appropriate but never this "gimme skin" move (that's what it is called).
The team initially was her BF, his sister, her BF's cousin and his newer wife. And they all just did high fives and fist bumps as appropriate. So her BF sister gets eased out and a close friend of her BF's cousins wife comes on as a substitute first and then as the regular. Her BF doesn't really know this girl (who is younger, like 19) but goes along with "gimme skin" as it is "no big thing", that she is just being "very friendly". BTW, the niece was never asked to join the team and has been told that her just even showing up to visit and root them on is not desired as it "looks like she's checking on him".
The niece, feeling hurt by this and that it "just didn't feel right" then talked to me.
I told her that I think that it's definitely flirting, that there's no such thing as "innocent flirting" when you have a SO, or even allowing someone to be extra friendly when you have an SO.... And showed her these:
Remember, this is a situation with a pending marriage engaged SO, not just some kids casually dating!