need ideas for a motocross birthday party for a 5 yr old

please help i need some idesa for a motocross birthday party. i don't know where to being. my 5 yrs old is totally into motocross. his whole room is done in it. he came to me the other day and said mom can i do my party in motocross? i told him i wasn't sure i would have to see what i can do. he said mom i know you can come up with something u always do. but i am clueless on this one. please help me! i don't want to let him down. any suggestions would be helpful! thank you!! monica :)