Sentence:  Depending on the crowd, a keg or <WSD>pony keg</WSD> may be the way to go. ... For fewer than 20 guests, consider a <WSD>pony keg</WSD>, which serves 80 drinks. 
Meaning of the word marked with <WSD> tags:  A container for beer holding 7.75 US gallons, equal to half the size of a standard beer keg.