USA have England, Iran and possibly Ukraine in the World Cup.
You couldn't pick 3 more teams to banter with, but Americans are either not creative enough or too scared to chant anything offensive. You really should learn from Britain, so here you go.
(Against Iran)
"You can't make weapons here! You can't make weapons here! You can't make weapons, can't make weapons, can't make weapons here! ... Yoooouuuuu can't make weapons here."
"We're more nuclear, we're more nuclear, we're more nuclear than you!"
"Where's your leader gone? Where's your leader gone?"
(Against England)
"We don't drink tea in Boston!"
"Hawaii is ours, Hawaii is oooouuuurrrrsss. United Kingdom, Hawaii is ours!" (this could also work against Wales/Scotland)
(Against Ukraine)
"**** off Democrats! **** off Democrats!" (This is for the Republicans)
"Just ask us for help! Just ask us for help! If you want to end the war then just ask us for help!" ermmhappy