The word “butt” has many different meanings in the English language. It can mean an overlapping joint, to strike or thrust, to place end to end, the end of a handle, the unused portion of something that is smoked, and of course, the fleshy backside of our bodies. But, the word “butt” also has a distinct meaning dealing with measurement.
The term “butt” was a Medieval unit of measure for wine casks, and the measurement was standardized in 1707. The largest unit, a tun (not to be mistaken for the weight measurement, ton), was about 252 wine gallons (953.92 liters). Other units were derived from there. A butt was half a tun, a puncheon was a third of a tun, a hogshead was a fourth of a tun, and two hogsheads made a butt (each 63 gallons, 238.48 liters). These were followed by a tierce, a barrel, and a rundlet, which all decrease in size.
So when you ask a friend to get you a “buttload” of something, it would measure about 126 gallons (476.96 liters). Be careful what you ask for if your friend is an expert in medieval measurements. You could end up with more than you could handle.