What means "slick" port style?

It is maybe a dumb question, but I'm asking this, because I heared about those port styles which are aviable in SBL designer - called exactly the same like in SBL designer, or also some people calling round port as "tube" port, or something like this, but I'm just never heared about "slick" port... So, what is a "slick" port?

Where did you find it?

Somebody asked me that if I could help with the design his slick-ported enclosure, but also I never heared about a slick port, so first I asked him, and he answered on that few people told him that slick ported enclosures are the most compact and the most effective compared to the others, so he wanna a slick-ported enclosure. After this I asked him that if slick port means small round port with huge flares, but he don't knew this...so...

Also I asked him that if it is "slipstream" port, which is donut-like round port with really huge flares and short length - like for example in JBL GT5 OEM enclosures, but he didn't knew this too. So, anyways, he want a slick ported enclosure...

He should at least show a photo. Sometimes in books, authors mean under "Slick port" a slick surface with zero friction force. Maybe that is it?

Maybe yes. Will ask him. Thank you for your help :)