Your friend has phrased the question wrong. Yes it is a trick question. It should be something like:
Think of words ending in "-gry". "Angry" and "hungry" are two of them. There are only three words in the English language. What is the third word?
The answer is "language". There are only 3 words in "the English language". The 3rd word being "language".
However, there are many words that DO end in gry:
affect-hungry fire-angry MacLoingry Seagry
aggry Gagry mad-angry self-angry
Agry girl-hungry mad-hungry selfe-angry
ahungry gonagry magry sensation-hungry
air-hungry gry malgry sex-angry
anhungry haegry man-hungry sex-hungry
Badagry half-angry managry Shchigry
Ballingry hangry mannagry shiggry
begry heart-angry Margry Shtchigry
bewgry heart-hungry maugry sight-hungry
boroughmongry higry pigry mawgry skugry
bowgry hogry meagry Sygry
braggry hogrymogry meat-hungry Tangry
Bugry hongry menagry Tchangry
Chockpugry hound-hungry messagry Tchigry
Cogry houngry music-hungry tear-angry
cony-gry huggrymuggry nangry th'angry
conyngry hund-hungry overangry tike-hungry
cottagry Hungry Bungry Pelegry Tingry
Croftangry hwngry Pingry toggry
diamond-hungry iggry Podagry ulgry
dog-hungry Jagry Pongry unangry
dogge-hungry job-hungry pottingry vergry
Dshagry kaingry power-hungry Vigry
Dzagry land-hungry profit-hungry vngry
eard-hungry Langry puggry war-hungry
Echanuggry leather-hungry pugry Wigry
Egry ledderhungry red-angry wind-hungry
euer-angry life-hungry rungry yeard-hungry
ever-angry Lisnagry scavengry yird-hungry
fenegry losengry Schtschigry Ymagry