Hi , I think the best description for this glass is an illusion glass or a deceptive glass , and could well have been used by a toastmaster ,the reduced amount of contents enabling him to remain sober,the glasses referred to a being banged on the table are called firing glasses , these do not necessarily have a deceptive bowl but are usually short sturdy glasses with a very thick foot , a 'Firing Foot' . these were normally used by all present at a gathering and banged on the table during toasts , the resulting sound being said to resemble a gun shot, or musket round, hence the term firing glass , if the 'Firing glass' used by the toastmaster had a deceptive bowl it would then be called a toastmaster firing glass.