What does it mean to be "Streets ahead"?
Solution 1:
They laughed at me when I asked what it meant.
They may have been referencing a clip from Community. In it, a character tries to popularize the phrase "streets ahead," but doesn't give a definition ("if you have to ask, you're streets behind").
Solution 2:
I don't know why it generated such laughter. In the UK at least, it's a very common, but neutral, way of saying "a long way in front" [in development/achievement/learning/etc.]. Perhaps [I'm guessing] from the days when news travelled more slowly, so someone in the centre of town was "streets ahead" in the local news? An example of modern usage: "Tom is streets ahead of the other kids is his class - he's already reading whole sentences."
Solution 3:
It is very widely used in the UK. There is even an entry in the OED for it, with examples from 1885 to 2005. Seems to have its origin in the late Victorian era.
One explanation I have seen on the web, possibly apocryphal, is that it dates from the time of town criers. The people whose job it was to call out the news started from the Town hall and moved outwards. The streets closest to the centre were 'streets ahead' of the outer places in being kept informed. This may or may not be its origin.
The OED meaning and examples are:
c. streets ahead (also better) : far ahead of someone or something, far superior.
1885 Freeman's Jrnl. (Dublin) 10 Oct. 6/6 M J Hayes..won streets ahead of a very weak opposition.
1898 Westm. Gaz. 1 Feb. 6/3 The English are better photographers than the Americans, but as regards mechanical ingenuity..the latter are streets ahead.
1911 Times 22 Apr. 8 In the matter of nutriment Manitobas were ‘streets’ ahead of any flour that could be produced from English wheat.
1958 Times 27 Oct. 4 His distribution was streets better than that of Greenwood, who was always in trouble.
2005 Daily Tel. 27 Oct. b 5 The company [sc. Toyota] is streets ahead of GM on profitability.
Solution 4:
With reference to WS2's answer, I can confirm that it is in common usage in the UK, and that I have found a reference that pre-dates those of the OED.
In The China Review of 1872/3 (p49) there is a passage as follows:
The half-dozen log cabins were the progenitors of long streets of shingle houses, and, if it possessed anything like a respectably metalled street (we are writing of two years ago) Omaha might lay some claim to its title of "City." As it is, or was, the cities of the "heathen Chinee" are many strokes (or streets) ahead of the Western settlement.
Incidentally, prior to 1880, I can not find any use of "strokes ahead" in anything other than a literal meaning in relation to either rowing or croquet, but perhaps "streets ahead" is a corruption of "strokes ahead"? I'm not convinced, but it's a possibility.
Solution 5:
It may come form a card game called cribbage in which the score board consists of streets on which you peg your score until reaching 120, each street is 30 points. You can be ahead by one or more streets or win by a street.