My wonderful Sullivan (now sadly pts) used to belong to a trekking centre and someone had taught him that when you rustled a polo packet and asked him Do you want a Polo? he would nod vigorously!!!! I used to cheat and rustle the polo packet and ask him Do you Love your Mummy? and (of course) he'd nod vigorously! You could also make him look a pratt by rustling the polo packet and asking Do you want the vet to come and stick a big nasty needle in you? and - natch - he'd nod vigorously!!! I loved that horse to bits and back again. RIP Sully x