Household Bleach
Somewhere in my memory I believe mixing a combination of cleaning products once caused massive liberation of Chlorine... quite interesting.
Acid and bleach. Chemists use this to generate chlorine gas in the lab. Or if not liquid bleach, then solid calcium hypochlorite or TCCA.
Or really, anything sufficiently oxidizing with hydrochloric acid, that doesn't make side products. (Example: MnO2.
Counter example: nitric acid, which makes nitrosyl chloride in part, which is the active ingredient in aqua regia, that can dissolve gold and platinum.)
The classic toxic cleaning agent combo is bleach and ammonia, which doesn't release chlorine, but something even worse, chloramine and nitrogen chlorides. These are about as reactive, but longer lasting, hence the use in water chlorination.
Hydrogen Peroxide and Bleach could provide some entertainment too... ?
The irony is that they're both oxidizers. But H2O2 can be a reducer, sometimes, resulting in O2 gas. This is such a case. Interestingly enough, that O2 is produced in the singlet state, which slowly decays to the triplet state. Deep red light is released in the process!
http://woelen.homescience.net/science/chem/exps/chemlum/index.htmlSodium hypochlorite is a strong oxidizer... a bit boring in aqueous form... maybe there is a way of making it more interesting?
Boil it to obtain chlorate, then add acid*?
*At your own risk. ClO2 is spontaneously explosive!
Tim