The first challenge in the AusCERT 2016 Shearwater CTF I tried was a fairly simple one, it said that the programming language was adults only and that the flag was in a file they offered for download. The contents were:
++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>++++++++++++++++++++++++++++++.>++++.-----------.++++++.++++++++++++++++++++.---------------------------------------------------------.++++++++++++++++++++++++++++++++++++.<-------.>>+++++++++++++++++.++++++++++.-----.<<+.>>++++++.<<-.>------------------.<+++++++++.<++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++.>---------.>>-.<-----------------.<++.>+++++++++++++++.<<+++++++++++++++++++++++++++++++++++++++++++++++++++++++++.++++.
It happens that due to my rather scattered experience I’d seen this rather hilarious language before, called brainfuck.
I found an online brainfuck interpreter and pasted it in, getting the flag.
flag{Bf_isn`t_Th@_sCaRy}