The way Randall came on to Jack was all done with double meaning. There was not one word which could be taken as not literally meaning what was said, as if sex were not on the menu and that it could always be taken that Jack had a dirty mind, reading things into what was not there, if Jack by chance took offence.
Just how it is in real life when married men get off with eachother. Its never "lets go off and !*#!". Its usually more
&
.

If Jack/Jake looked at me like that, I would be thinking "Yay, it's my lucky night!!"

And it wasn't just the once, the looks were going back and forth between them, but that's all it was, just looks, so they weren't being too blatant, but just enough to make sure each of them knew what was on the other's mind

And the scene outside, Randall doesn't actually suggest anything other than just two buddies going fishing for the weekend (which is exactly what Jack and Ennis did, as far as anyone else is concerned), but they were both on the same wavelength enough to know what it really meant

I also think when Jack says about women powdering their nose to go home and go to bed could have been a hint that Randall picked up on, the reason most women would powder their nose (as in fixing their make-up/hair) when leaving a party would be to look attractive to go home and go to bed with her husband, the fact that Jack didn't realise, or care, that that was what Lureen was doing would have implied to Randall that Jack wasn't all that interested in Lureen sexually (especially when you add it to Lureen's comment about husbands not wanting to dance with their wives).
On the subject of Randall, excited as I am at the thought of the deleted scenes on the new DVD, I'm not sure I really want to see the scene of Jack and Randall hugging (if it does indeed exist). I'm not as anti-Randall as I once was, I can accept him and Jack having something approaching a proper relationship, rather than just meaningless sex, but I'm not sure I want to actually see any evidence of it