"Fugu? Is that you, Fugu?" "Salmon? I’ll be damned. I haven’t seen you since high school. How are you?"
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means surprised, so the verb vocab version is to be surprised.
What are you so surprised by? Your friend's odor (おどろ). Think of a friend that you wouldn't expect to be so smelly. Then, be surprised by the odor. Eww, bro, you have to take a shower.