Sullivan then simulated a man upchucking.
Morgan laughed before politely answering questions for the local CBS affiliate. After all, he was being mocked for his resilience. On Monday, Morgan threw up then slumped into the huddle and blocked on two straight running plays.
"As long as you get back in there, it's going to wear off," the sixth-round choice from Virginia Tech said of his nausea. Sullivan's mockery had two purposes. He wanted to lighten the mood of an arduous training camp and he was trying to knock the sheen off of his star pupil.
Sullivan constantly rides Morgan, hoping to keep the training camp upstart humble and innocent.
"You've been around guys where you thought, 'That guy is going to be a player,"' Sullivan said. "And two years later, you think, 'I thought that guy was going to be a good player?"'
O'Sullivan wants no such thing happening to Morgan, who shines in an otherwise dim offense struggling to learn coordinator Mike Martz's complex scheme. Morgan led the team with four catches for 68 yards in the 49ers' 18-6 exhibition opening-night loss in Oakland.
The sixth-round pick from Virginia Tech was back at it Tuesday, punctuating a crisp two-minute drive by leaping over starting cornerback Nate Clements for a touchdown pass from quarterback J.T. O'Sullivan.
With Isaac Bruce and Arnaz Battle limited to one practice a day because of age and injury respectively and unrestricted free agent Bryant Johnson idled with a strained hamstring, Morgan pounced on the opportunity and seems to be learning the Martz and Sullivan nuances.
In the Martz scheme a receiver could possibly run three different routes on any given play. A change in the team's protection could alter his route, so could the coverage and even how the cornerback lines up.
And in the Martz offense everything must be exact. A 18-yard route means 18 yards not 18 and a quarter.
"There are routes where you have got to go 8 to 10 yards at an angle and you got to be 2 yards away from the hash too," Morgan said. And then his eyes got big. "And you got to get there."
It's an avalanche of information for him, particularly coming from Virginia Tech and an offense that uses few routes and allows its receivers to "free lance" according to Morgan. He often stays late in Sullivan's meeting room so the coach can show him how other receivers he has coached execute his techniques.
In fact, Morgan can't get Sullivan out of his head.
"The more competition you get, the more you think about coach Sullivan and the technique things he's trying to tell you," Morgan said. "The small things that don't really even matter, that's when they come into play."
Ever since his arrival at Virginia Tech, Morgan's been involved in competition. He struggled for passes with Eddie Royal (Broncos' second-round pick) and Justin Harper (Ravens' seventh-round), so he was used to fighting to stand out.
He tries to keep in contact with his former teammates, particularly Royal. They exchanged Bible verses by texting, something they started doing after the Virginia Tech tragedy on April 16 of last year, when a student killed 32 people on campus. Gun man Cho Seung-Hui attended Royal's high school and two co-eds Royal knew died.
Morgan was two buildings away from where most of the killing occurred. When he heard the gun shots, he fled to the apartment of a teammate and began feverishly calling his college friends, who were spared.
"It's the worst thing I've ever had to deal with and I've lost a lot of friends," said Morgan, who grew up in a crime addled section of Washington D.C.
Now, Morgan doesn't have an opportunity to think about much more than football.
"I'm getting there," Morgan said of his learning curve in camp. "I still have a lot of work to do."