For years and years, campers have enjoyed inventing fun responses to being bopped on the hand.
a(b()) =
c(d()) =
a(e(f())) =
g(h(d())) =
i(e(g())) =
i(e(d(f()))) =
c(e(b(a()))) =
i(a(b(d(c())))) =
h(e(f(e(h())))) =
g(c(d(h(f()))))
a(e(i(d())))
f(g(c()))
h(g(a(f(g()))))
i(a(g(h())))
b(e(b(i(f()))))
e(g(b(h())))
e(g(d(i(f()))))
b(e(b(e(b(e(b()))))))
b(g(i(d())))
e(c(h()))