Probably something like this:
rem get input
input "Are you gay? --> ";answer$
rem make lower case (changes "yEs" or "YES" into "yes")
answer$ = lower$( answer$ )
rem process input
if answer$ = "yes"
print "Hahahahha FAGGOT"
else
print "Incorrect answer, you are very obviously gay."
endif
Also, you should try and account for different versions of a question. For example, I could write "yes", "yep", "eeyup", "yeah" or something else. Obses87 wrote a very cool function for this, check it out here :
http://forum.thegamecreators.com/?m=forum_view&t=197488&b=10
TheComet