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 Englishpub 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.