The informant described a ritual where people taking a shot together tap their shot glass on the table before saying “cheers” and taking the shot. This is done any time taking a shot of alcohol with others, including friends and family, no matter the place or time. This is done to signal everyone to take their shot and as an announcement of celebration, of sorts. “Cheers” is often said to encourage good will as one drinks, and the meaning is the same here.
The ritual demonstrates a culture which engages with alcohol as a means of celebration. The involved parties want to encourage good will and acknowledge celebration as they dive deeper into their party-atmosphere cultivated by alcohol by saying “cheers” and clinking glasses on the table. There is no magic necessarily associated, just a soft of acknowledgment of good will. The sound made serves two purposes, it seems. One, to signal everyone to take the shot so they can time the drink to be taken at the same time. Second, to signal celebration in the same way that a “woop” does. Noises to announce a celebration are common, such as clapping, “wooping,” whistling, clinking glasses, etc… These are not necessarily to start a celebration but for the announcement of continuation of a celebration. The ritual is widely spread, at least around the United States. Other cultures have similar versions, saying something that imitates a sort of blessing before drinking. This is likely due to the spread of the ritual as folklore, stemming from a traditional blessing around food and drink.