THINK-TANK: To confirm my opinion, I order you to eat it.
 
OMEGA: (gulping) Eat it?
 
THINK-TANK: Do you doubt the Mighty Think-Tank?
 
OMEGA: Oh, no, no. But poor Lieutenant Iota has not had her breakfast. Lieutenant Iota, I order you to eat this — this sandwich.
 
IOTA: (dubiously) Eat it? Oh, Captain! It’s a very great honour to be the first Martian to eat a sandwich, I’m sure, but — but how can I be so impolite as to eat before my Sergeant? (handing Oop the book and saying brightly) Sergeant Oop, I order you to eat the sandwich immediately.
Explanation:
 
Think-Tank eventually ordered Omega to consume the book to ensure it was eatable (sandwich). Omega was terrified since she couldn't decide whether or not to consume the book. It's because, although accepting her master's statement that the weird thing (book) was an eatable, Omega was unsure of it, so she gulped, demonstrating her nervousness. When Think-Tank noted her pause, he inquired whether she doubted his statements ('The strange item (book) was a sandwich'). Omega deftly diverted her master's wrath by claiming Iota had not eaten her meal after listening to her master. So, as a result, Omega quickly instructed Iota to eat the sandwich (book).
 
Despite this, Iota managed to get away without eating the sandwich. Sergeant Oop was ordered to eat the sandwich because Iota felt it would be disrespectful to eat before the Sergeant. This demonstrates that Iota was not convinced by her master's assumption (claiming 'book' to be a sandwich).
 
The 'humour' of the play is highlighted in the above dialogues. In addition, it emphasises two points. Though the crew members appear to accept Think-Tank's decisions and claim that he is bright, they do not regard him as such. Second, Think-Tank was depicted as a humorous character.
Reference:
National Council of Educational Research and Training (2007). The Book That Saved The Earth - Claire Boiko (pp 63-73). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.