The "stuff" of the title of Mick Cooper's play is the substance that Toby is unable to provide but Xav is offering to supply in order to make Toby's wife Jess pregnant.
Nothing unsavoury is being offered—Xav has had his sperm frozen at a local clinic as he is terminally ill and wants to, well, leave something of himself behind, and he has asked the clinic to give his best friends first refusal.
Actually Xav and Jess go back a long way and there was even one time, pre-Toby, when they slept together, but this isn't what bothers ex-soldier Toby. More it is the wounded macho pride of being infertile combined with the fact that Xav, whose genetic offspring he may have to bring up, is a bit of an idiot.
It's a great idea with plenty of comic potential and there is some good comedy writing here, but there is a tendency for both writer and director (Gregg Aled Scott) to force in a laugh at every opportunity. The title is given to the life-giving fluid because every time Xav mentions it he uses a different odd slang term; the first few times it may make you laugh or cringe, depending on your taste, but it soon becomes tiresome.
There are also some parts that go into comic routines or comic styles of delivery, some used frequently in pantomime, that distract from the basic realism of the scenes. When we get down to the serious scenes, everyone is suddenly being a bit too open and frank with one another to be believable.
There are some very natural, believable performances, though, from Eve Burley as Jess and Danny Ryder as Toby. Karl Greenwood plays Xav perfectly well as the character is written, but this is a person who is annoying in an exhausting way from the moment he enters the room, and so he can become rather wearing for the audience too.
Having said that, there is a lot in this play that is entertaining and well-performed, so it is worth a look.