To think I was planning something else tonight....I will compile a small list as already several examples come to mind and I'm sure there are many more recorded (from Swirled News)

"Circular Stories, Facts and Figures"

Eye-witnesses: There are around two dozen eye-witness accounts of crop circles forming. All describe similar events; an invisible force coming out of nowhere in otherwise calm conditions and spinning the crops down within seconds, usually with surprising violence - yet little damage is found in the laid crop. Tornado-like funnels, light phenomena and high-pitched whistling sounds have also been reported.

(Your friends managed THIS??)
Quick on the draw: In July 1996, a 915 feet spiral of 151 circles appeared in full view of the busy A303 road, opposite England's ancient monument Stonehenge, Wiltshire, within a 45 minute period one Sunday afternoon. A pilot, gamekeeper and security guard confirmed it had not been there before 5.30pm - yet shortly after 6.00pm, the massive formation was being spotted by passing tourists. Much smaller man-made designs have taken several hours to complete. This also disproves the myth that all crop circles appear by night.

(Hmmm.... almost a mile long.....guess your "friend" had a bunch of his buddies helping him THAT night!)
Longest crop formation: This occurred at Etchilhampton, Wiltshire, in 1996 - a chain of circles and pathways approximately 4100 feet long crossed from one end of a field to another.

(Hmmmm....six men in barely 4 hours of darkness had to produce at least 68 circles each, and leave no marks!)
Largest design and most circles in one formation: The record for both these qualities is currently held by the huge motif at Milk Hill, Wiltshire, August 12th 2001 - 409 small circles made up a staggering six-armed design of around 800 feet diameter.

Largest expanse of laid crop in one design: A seven-petalled mandala which appeared at Alton Barnes, Wiltshire, in 1998 contained an unbroken flattened area covering 6000 square metres.
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Yup, you're friends must be preeetty busy..........;~)