In an Irish bar, a drink that's half Guinness and half lager. Not called a "black and tan" since those colors commemorate the british military force used to supress Irish uprisings.
In an English pub I'll order a black and tan, but in an Irish establishment, I'll order a half and half.
A drug cocktail containing one half a 30mg Adderall and one half a 10mg Valium. The effect is a balance of the best aspects of cocaine and ecstasy. A counter-intuitive mix as the pharmaceuticals work at cross purposes, but the synergy induces a euphoric energy which is free from anxiety. Impaired memory is a side effect of the Valium, which can be another benefit, depending on what you did whilst under the influence of the cocktail.
A culinary delightthought to originate from Cardiff. Involves having half rice and half chips with your Curry.
Cardiff Boyo: Aw I'll haves a chicken tikkia masala,like
Waiter: With rice?
Cardiff Boyo: Nah half and half innit
Waiter: Ok
Cardiff Boyo: Safe as fuck.