It's not challenging! I'm sure you could understand it.
I said 'Legitimate', so you'd have to say something that started with 'te', because 't' and 'e' are the last two letters of 'legitimate'. If you said something like 'Tennis', someone would have to respond with something that began with 'is', because 'i' and 's' are the two last letters of 'tennis'. They might say 'isolation'... then 'o' and 'n'... and so on!
Hope that helps!